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A003849 -id:A003849 - OEIS
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A005614 The binary complement of the infinite Fibonacci word A003849. Start with 1, apply 0->1, 1->10, iterate, take limit. +20
83
1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,1
COMMENTS
Previous name was: The infinite Fibonacci word (start with 1, apply 0->1, 1->10, iterate, take limit).
Characteristic function of A022342. - Philippe Deléham, May 03 2004
a(n) = number of 0's between successive 1's (see also A003589 and A007538). - Eric Angelini, Jul 06 2005
With offset 1 this is the characteristic sequence for Wythoff A-numbers A000201=[1,3,4,6,...].
Eric Angelini's comment made me think that if 1 is defined to be the number of 0's between successive 1's in a string of 0's and 1's, then this string is 101. Applying the same operation to the digits of 101 leads to 101101, the iteration leads to successive palindromes of lengths given by A001911, up to a(n). - Rémi Schulz, Jul 06 2010
For generalized Fibonacci words see A221150, A221151, A221152, ... - Peter Bala, Nov 11 2013
The limiting mean of the first n terms is phi - 1; the limiting variance is phi (A001622). - Clark Kimberling, Mar 12 2014
Apply the difference operator to every column of the Wythoff difference array, A080164, to get an array of Fibonacci numbers, F(h). Replace each F(h) with h, and apply the difference operator to every column. In the resulting array, every column is A005614. - Clark Kimberling, Mar 02 2015
Binary expansion of the rabbit constant A014565. - M. F. Hasler, Nov 10 2018
REFERENCES
J.-P. Allouche and J. Shallit, Automatic Sequences, Cambridge Univ. Press, 2003.
G. Melançon, Factorizing infinite words using Maple, MapleTech journal, vol. 4, no. 1, 1997, pp. 34-42, esp. p. 36.
LINKS
T. D. Noe, Table of n, a(n) for n = 0..10945 (19 iterations)
Ricardo Gómez Aíza, Symbolic dynamical scales: modes, orbitals, and transversals, arXiv:2009.02669 [math.DS], 2020.
F. Axel et al., Vibrational modes in a one dimensional "quasi-alloy": the Morse case, J. de Physique, Colloq. C3, Supp. to No. 7, Vol. 47 (Jul 1986), pp. C3-181-C3-186; see Eq. (10).
E. A. Bender and J. T. Butler, Asymptotic approximations for the number of fanout-free functions, IEEE Trans. Computers, 27 (1978), 1180-1183. (Annotated scanned copy)
M. Bunder and K. Tognetti, On the self matching properties of [j tau], Discrete Math., 241 (2001), 139-151.
Glen Joyce C. Dulatre, Jamilah V. Alarcon, Vhenedict M. Florida, and Daisy Ann A. Disu, On Fractal Sequences, DMMMSU-CAS Science Monitor (2016-2017) Vol. 15 No. 2, 109-113.
S. Dulucq and D. Gouyou-Beauchamps, Sur les facteurs des suites de Sturm, Theoret. Comput. Sci. 71 (1990), 381-400.
M. S. El Naschie, Statistical geometry of a Cantor discretum and semiconductors, Computers & Mathematics with Applications, Vol. 29 (Issue 12, June 1995), 103-110.
D. Gault and M. Clint, "Curiouser and curiouser" said Alice. Further reflections on an interesting recursive function, Internat. J. Computer Math., 26 (1988), 35-43.
D. Gault and M. Clint, "Curiouser and curiouser said Alice. Further reflections on an interesting recursive function, Intern. J. Computer. Math., 26 (1988), 35-43. (Annotated scanned copy)
J. Grytczuk, Infinite semi-similar words, Discrete Math. 161 (1996), 133-141.
Clark Kimberling, Intriguing infinite words composed of zeros and ones, Elemente der Mathematik (2021).
Clark Kimberling and K. B. Stolarsky, Slow Beatty sequences, devious convergence, and partitional divergence, Amer. Math. Monthly, 123 (No. 2, 2016), 267-273.
K. L. Kodandapani and S. C. Seth, On combinational networks with restricted fan-out, IEEE Trans. Computers, 27 (1978), 309-318. (Annotated scanned copy)
Wolfdieter Lang, The Tribonacci and ABC Representations of Numbers are Equivalent, arXiv preprint arXiv:1810.09787 [math.NT], 2018.
G. Melançon, Lyndon factorization of sturmian words, Discr. Math., 210 (2000), 137-149.
S. Mneimneh, Fibonacci in The Curriculum: Not Just a Bad Recurrence, in Proceeding SIGCSE '15 Proceedings of the 46th ACM Technical Symposium on Computer Science Education, 253-258.
C. Mongoven, The Rabbit Sequence (a musical composition with A005614).
José L. Ramírez, Gustavo N. Rubiano, and Rodrigo de Castro, A Generalization of the Fibonacci Word Fractal and the Fibonacci Snowflake, arXiv preprint arXiv:1212.1368 [cs.DM], 2012-2014.
Jeffrey Shallit, Characteristic words as fixed points of homomorphisms, University of Waterloo Technical Report CS-91-72, 1991.
Jeffrey Shallit, Characteristic words as fixed points of homomorphisms. [Cached copy, with permission]
N. J. A. Sloane, Families of Essentially Identical Sequences, Mar 24 2021 (Includes this sequence)
K. B. Stolarsky, Beatty sequences, continued fractions and certain shift operators, Canad. Math. Bull., 19 (1976), 473-482.
Scott V. Tezlaf, On ordinal dynamics and the multiplicity of transfinite cardinality, arXiv:1806.00331 [math.NT], 2018. See p. 10.
Eric Weisstein's World of Mathematics, Rabbit Constant and Rabbit Sequence.
FORMULA
Define strings S(0)=1, S(1)=10, thereafter S(n)=S(n-1)S(n-2); iterate. Sequence is S(oo). The individual S(n)'s are given in A036299.
a(n) = floor((n+2)*u) - floor((n+1)*u), where u = (-1 + sqrt(5))/2.
Sum_{n>=0} a(n)/2^(n+1) = A014565. - R. J. Mathar, Jul 19 2013
From Peter Bala, Nov 11 2013: (Start)
If we read the present sequence as the digits of a decimal constant c = 0.101101011011010 ... then we have the series representation c = Sum_{n >= 1} 1/10^floor(n*phi). An alternative representation is c = Sum_{n >= 1} 1/10^floor(n/phi) - 10/9.
The constant 9*c has the simple continued fraction representation [0; 1, 10, 10, 100, 1000, ..., 10^Fibonacci(n), ...]. See A010100.
Using this result we can find the alternating series representation c = 1/9 - 9*Sum_{n >= 1} (-1)^(n+1)*(1 + 10^Fibonacci(3*n+1))/( (10^(Fibonacci(3*n - 1)) - 1)*(10^(Fibonacci(3*n + 2)) - 1) ). The series converges very rapidly: for example, the first 10 terms of the series give a value for c accurate to more than 5.7 million decimal places. Cf. A014565. (End)
a(n) = A005206(n+1) - A005206(n). a(2*n) = A339052(n); a(2*n+1) = A339051(n+1). - Peter Bala, Aug 09 2022
EXAMPLE
The infinite word is 101101011011010110101101101011...
MAPLE
Digits := 50; u := evalf((1-sqrt(5))/2); A005614 := n->floor((n+1)*u)-floor(n*u);
MATHEMATICA
Nest[ Flatten[ # /. {0 -> {1}, 1 -> {1, 0}}] &, {1}, 10] (* Robert G. Wilson v, Jan 30 2005 *)
Flatten[Nest[{#, #[[1]]} &, {1, 0}, 9]] (* IWABUCHI Yu(u)ki, Oct 23 2013 *)
SubstitutionSystem[{0 -> {1}, 1 -> {1, 0}}, {1, 0}, 9] // Last (* Jean-François Alcover, Feb 06 2020 *)
PROG
(PARI) a(n, w1, s0, s1)=local(w2); for(i=2, n, w2=[ ]; for(k=1, length(w1), w2=concat(w2, if(w1[ k ], s1, s0))); w1=w2); w2
for(n=2, 10, print(n" "a(n, [ 0 ], [ 1 ], [ 1, 0 ]))) \\ Gives successive convergents to sequence
(PARI) /* for m>=1 compute exactly A183136(m+1)+1 terms of the sequence */
r=(1+sqrt(5))/2; v=[1, 0]; for(n=2, m, v=concat(v, vector(floor((n+1)/r), i, v[i])); a(n)=v[n]; ) /* Benoit Cloitre, Jan 16 2013 */
(Haskell)
a005614 n = a005614_list !! n
a005614_list = map (1 -) a003849_list
-- Reinhard Zumkeller, Apr 07 2012
(Magma) [Floor((n+1)*(-1+Sqrt(5))/2)-Floor(n*(-1+Sqrt(5))/2): n in [1..100]]; // Vincenzo Librandi, Jan 17 2019
(Python)
from math import isqrt
def A005614(n): return (n+isqrt(m:=5*(n+2)**2)>>1)-(n+1+isqrt(m-10*n-15)>>1) # Chai Wah Wu, Aug 17 2022
CROSSREFS
Binary complement of A003849, which is the standard form of this sequence.
Two other essentially identical sequences are A096270, A114986.
Subwords: A178992, A171676.
Cf. A000045 (Fibonacci numbers), A001468, A001911, A005206 (partial sums), A014565, A014675, A022342, A036299, A044432, A221150, A221151, A221152.
Cf. A339051 (odd bisection), A339052 (even bisection).
The following sequences are all essentially the same, in the sense that they are simple transformations of each other, with A000201 as the parent: A000201, A001030, A001468, A001950, A003622, A003842, A003849, A004641, A005614, A014675, A022342, A088462, A096270, A114986, A124841. - N. J. A. Sloane, Mar 11 2021
KEYWORD
nonn,easy,nice
AUTHOR
EXTENSIONS
Corrected by Clark Kimberling, Oct 04 2000
Name corrected by Michel Dekking, Apr 02 2019
STATUS
approved
A316342 Fibonacci word A003849 with first two terms replaced by 2's. +20
23
2, 2, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,1
COMMENTS
A word that is morphic; but neither pure morphic, uniform morphic, primitive morphic, nor recurrent.
LINKS
Jean-Paul Allouche, Julien Cassaigne, Jeffrey Shallit, Luca Q. Zamboni, A Taxonomy of Morphic Sequences, arXiv preprint arXiv:1711.10807, Nov 29 2017
CROSSREFS
Cf. A003849.
Sequences mentioned in the Allouche et al. "Taxonomy" paper, listed by example number: 1: A003849, 2: A010060, 3: A010056, 4: A020985 and A020987, 5: A191818, 6: A316340 and A273129, 18: A316341, 19: A030302, 20: A063438, 21: A316342, 22: A316343, 23: A003849 minus its first term, 24: A316344, 25: A316345 and A316824, 26: A020985 and A020987, 27: A316825, 28: A159689, 29: A049320, 30: A003849, 31: A316826, 32: A316827, 33: A316828, 34: A316344, 35: A043529, 36: A316829, 37: A010060.
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jul 14 2018
STATUS
approved
A316825 Fibonacci word A003849 with its initial term changed to 2. +20
23
2, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,1
COMMENTS
A word that is pure morphic, but neither uniform morphic, primitive morphic, nor recurrent.
LINKS
CROSSREFS
Cf. A003849.
Sequences mentioned in the Allouche et al. "Taxonomy" paper, listed by example number: 1: A003849, 2: A010060, 3: A010056, 4: A020985 and A020987, 5: A191818, 6: A316340 and A273129, 18: A316341, 19: A030302, 20: A063438, 21: A316342, 22: A316343, 23: A003849 minus its first term, 24: A316344, 25: A316345 and A316824, 26: A020985 and A020987, 27: A316825, 28: A159689, 29: A049320, 30: A003849, 31: A316826, 32: A316827, 33: A316828, 34: A316344, 35: A043529, 36: A316829, 37: A010060.
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jul 14 2018
STATUS
approved
A085357 Common residues of binomial(3n,n)/(2n+1) modulo 2: relates ternary trees (A001764) to the infinite Fibonacci word (A003849). +20
16
1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,1
COMMENTS
The n-th runs of ones is given by: 3 - A003849(n) (infinite Fibonacci word) = A076662(n+1). Runs of zeros are given by: A085358 and are also directly related to the Fibonacci sequence. Coefficients of A(x)^3 are found in A085359.
a(n) = 0 iff some binary digit of n is 1 while the corresponding binary digit of 3*n is 0. - Robert Israel, Jul 12 2016
The Run Length Transform of [0,1,0,0,0,...], A063524, the characteristic function of 1. (See A227349 for the definition). - Antti Karttunen, Oct 15 2016
LINKS
J.-P. Allouche, F. v. Haeseler, H.-O. Peitgen, A. Petersen and G. Skordev, Automaticity of double sequences generated by one-dimensional linear cellular automata, Theoret. Comput. Sci. 186 (1997), 195-209.
J.-P. Allouche, F. v. Haeseler, H.-O. Peitgen and G. Skordev, Linear cellular automata, finite automata and Pascal's triangle, Discrete Appl. Math. 66 (1996), 1-22.
R. Bacher, C. Reutenauer, The number of right ideals of given codimension over a finite field, in Noncommutative Birational Geometry, Representations and Combinatorics, edited by Arkady. Berenstein and Vladimir. Retakha, Contemporary Mathematics, Vol. 592, 2013.
Paul Tarau, Emulating Primality with Multiset Representations of Natural Numbers, in Theoretical Aspects of Computing, ICTAC 2011, Lecture Notes in Computer Science, 2011, Volume 6916/2011, 218-238, DOI: 10.1007/978-3-642-23283-1_15.
FORMULA
G.f.: 1 + x*A(x)^3 = A(x) (Mod 2); a(n) = A001764(n) (Mod 2).
a(n) = binomial(3n, n) (mod 2). Characteristic function of Fibbinary numbers (i.e. a(n)=1 iff n is in A003714). - Benoit Cloitre, Nov 15 2003
Recurrence: a(0) = 1, a(2n) = a(4n+1) = a(n), a(4n+3) = 0.
a(n-2) = A000256(n)(mod 2), for n>2. - John M. Campbell, Jul 08 2016
a(n) = A000621(n+1)(mod 2). - John M. Campbell, Jul 15 2016
a(n) = A000625(n)(mod 2). - John M. Campbell, Jul 15 2016
a(n) = A008966(A005940(1+n)). [Follows from the Run Length Transform interpretation, see also A277010.] - Antti Karttunen, Oct 15 2016
a(n) = abs(A132971(n)) = abs(A008683(A005940(1+n))). - Antti Karttunen, May 30 2017
MAPLE
f:= proc(n) local L, Lp;
L:= convert(n, base, 2);
Lp:= convert(3*n, base, 2);
if has(L-Lp[1..nops(L)], 1) then 0 else 1 fi
end proc:
map(f, [$0..100]); # Robert Israel, Jul 12 2016
MATHEMATICA
Table[Mod[Binomial[3 n, n], 2], {n, 0, 120}] (* Michael De Vlieger, Jul 08 2016 *)
PROG
(Magma) [Binomial(3*n, n) mod 2: n in [0..100]]; // Vincenzo Librandi, Jul 09 2016
(PARI) A085357(n) = !bitand(n, n<<1); \\ Antti Karttunen, Aug 22 2019
CROSSREFS
Cf. A001764 (ternary trees), A085358 (runs of zeros), A076662 (runs of ones), A003849 (infinite Fibonacci word), A085359 (A(x)^3).
Absolute values of A132971.
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jun 25 2003
STATUS
approved
A182028 Take first n bits of the infinite Fibonacci word A003849, regard them as a binary number, then convert it to base 10. +20
8
0, 1, 2, 4, 9, 18, 37, 74, 148, 297, 594, 1188, 2377, 4754, 9509, 19018, 38036, 76073, 152146, 304293, 608586, 1217172, 2434345, 4868690, 9737380, 19474761, 38949522, 77899045, 155798090, 311596180, 623192361, 1246384722, 2492769444, 4985538889, 9971077778 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
COMMENTS
a(n) mod 2 = A003849(n);
a(n) = A000225(n+1) - A044432(n).
LINKS
FORMULA
a(n) = 2*a(n-1) + A003849(n) for n > 0, a(0) = 0.
EXAMPLE
0 -> 0 -> a(0) = 0,
0,1 -> 01 -> a(1) = 1,
0,1,0 -> 010 -> a(2) = 2,
0,1,0,0 -> 0100 -> a(3) = 4,
0,1,0,0,1 -> 01001 -> a(4) = 9,
0,1,0,0,1,0 -> 010010 -> a(5) = 18,
0,1,0,0,1,0,1 -> 0100101 -> a(6) = 37
0,1,0,0,1,0,1,0 -> 01001010 -> a(7) = 74
0,1,0,0,1,0,1,0,0 -> 010010100 -> a(8) = 148,
0,1,0,0,1,0,1,0,0,1 -> 0100101001 -> a(9) = 297.
MATHEMATICA
nesting = 7; A003849 = Flatten[Nest[{#, #[[1]]}&, {0, 1}, nesting]]; a[n_] := FromDigits[Take[A003849, n+1], 2]; Table[a[n], {n, 0, Length[A003849] - 1}] (* Jean-François Alcover, Feb 13 2016 *)
PROG
(Haskell)
a182028 n = a182028_list !! n
a182028_list = scanl1 (\v b -> 2 * v + b) a003849_list
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Reinhard Zumkeller, Apr 07 2012
STATUS
approved
A187200 Parse the Fibonacci word A003849 into distinct phrases 0, 1, 00, 10, 100, 1001, 01, 001, 010, ...; a(n) = length of n-th phrase. +20
7
1, 1, 2, 2, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 5, 4, 5, 5, 6, 6, 5, 5, 6, 6, 7, 7, 7, 8, 7, 6, 8, 9, 6, 6, 10, 7, 8, 8, 7, 8, 7, 11, 7, 9, 8, 9, 8, 10, 9, 8, 9, 8, 9, 9, 9, 12, 10, 10, 9, 10, 9, 11, 10, 13, 12, 10, 10, 11, 11, 11, 10, 11, 11, 14, 11, 12, 12, 11, 13, 10, 12, 12, 11, 12, 13, 12, 13, 14, 13, 11, 13, 14, 15, 14, 13, 16, 15, 12, 12, 17 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
LINKS
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Mar 06 2011
STATUS
approved
A284749 {001->2}-transform of the infinite Fibonacci word A003849. +20
7
0, 1, 2, 0, 1, 2, 2, 0, 1, 2, 0, 1, 2, 2, 0, 1, 2, 2, 0, 1, 2, 0, 1, 2, 2, 0, 1, 2, 0, 1, 2, 2, 0, 1, 2, 2, 0, 1, 2, 0, 1, 2, 2, 0, 1, 2, 2, 0, 1, 2, 0, 1, 2, 2, 0, 1, 2, 0, 1, 2, 2, 0, 1, 2, 2, 0, 1, 2, 0, 1, 2, 2, 0, 1, 2, 0, 1, 2, 2, 0, 1, 2, 2, 0, 1, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
COMMENTS
From Dan Rust, Aug 18 2018: (Start)
This word is the fixed point of the morphism 0->2, 1->01, 2->2201 with the finite string 0, 1, 2, 0, 1 appended to the beginning. This morphism comes from taking the 'proper' version of the Fibonacci morphism 0->01, 1->1, given by 0->001, 1->01 (A189661 but with the rightmost 0 moved to the left of each image word), then replacing 001 with 2 and noting that the new symbol 2 should map to 00100101 = 2201 in order to be consistent.
The finite string appended to the beginning comes from the process of finding a proper version of the Fibonacci morphism using a return word encoding and taking conjugates which causes a shift of the respective fixed points.
(End)
This sequence is the unique fixed point of the morphism 0->01, 1->2, 2->0122. See the paragraph following Lemma 23 in the paper by Allouche and me. - Michel Dekking, Oct 05 2018
LINKS
J.-P. Allouche, F. M. Dekking, Generalized Beatty sequences and complementary triples, arXiv:1809.03424v3 [math.NT], 2018-2019.
EXAMPLE
As a word, A003849 = 01001010010010100..., and replacing each 001 by 2 gives 01201220120...
MATHEMATICA
s = Nest[Flatten[# /. {0 -> {0, 1}, 1 -> {0}}] &, {0}, 13] (* A003849 *)
w = StringJoin[Map[ToString, s]]
w1 = StringReplace[w, {"001" -> "2"}]
st = ToCharacterCode[w1] - 48 (* A284749 *)
Flatten[Position[st, 0]] (* A214971 *)
Flatten[Position[st, 1]] (* A284624 *)
Flatten[Position[st, 2]] (* A284625 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, May 02 2017
STATUS
approved
A284620 {00->2}-transform of the infinite Fibonacci word A003849. +20
5
0, 1, 2, 1, 0, 1, 2, 1, 2, 1, 0, 1, 2, 1, 0, 1, 2, 1, 2, 1, 0, 1, 2, 1, 2, 1, 0, 1, 2, 1, 0, 1, 2, 1, 2, 1, 0, 1, 2, 1, 0, 1, 2, 1, 2, 1, 0, 1, 2, 1, 2, 1, 0, 1, 2, 1, 0, 1, 2, 1, 2, 1, 0, 1, 2, 1, 2, 1, 0, 1, 2, 1, 0, 1, 2, 1, 2, 1, 0, 1, 2, 1, 0, 1, 2, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
COMMENTS
From Michel Dekking, Mar 17 2020: (Start)
This sequence is a morphic sequence, i.e., the letter-to-letter image of the fixed point of a morphism mu. In fact, one can take the alphabet {A,B,C,D} with the morphism
mu: A->AB, B->CD, C->ABCD, D->CD,
and the letter-to-letter map lambda defined by
lambda: A->0, B->1, C->2, D->1.
Then (a(n)) = lambda(x), where x = ABCDABCDCD... is the unique fixed point of the morphism mu.
How does one see this? The infinite Fibonacci word
x_F = A003849 = 0100101001001....
can be written as a concatenation of the two words 01 and 001.
In fact, if beta is the Fibonacci morphism 0->01, 1->0, then beta(01)=010, beta(001)=01010, from which this can be read off.
This can also be found in Lemma 23 in Allouche and Dekking, which gives, moreover, that if we define the morphism g on the alphabet {a,b} by
g(a) = ab, g(b) =abb
then a(n) = delta(x_G(n)), where
x_G = ababbababb...
is the unique fixed point of g, and delta is the map
delta(a) = 01, delta(b) = 21.
In my paper "Morphic words,..." such a map delta is called a decoration.
It is well-known that decorated fixed points are morphic sequences, and the 'natural' algorithm to achieve this splits a in AB, and b in CD. This gives the morphism mu on the alphabet {A,B,C,D}, and the letter-to-letter map lambda.
We next prove the first conjecture by Kimberling. We easily see from the form of mu that the letters B and D occur, and only occur, at even positions in the fixed point x of mu. Since lambda(B)=lambda(D)=1, and A and C are not mapped to 1, it follows immediately that the positions of 1 in (a(n)) are given by A005843 = (2n).
For a proof of Kimberling's second conjecture, note that a(n)=2 iff x(n)=C, where x is the fixed point of mu. The return words of C in x are CD and CDAB. Coding these two return words by their lengths, mu induces a descendant morphism tau given by
tau(2) = 24, tau(4) = 244.
We see that tau is just an alphabet change of the morphism g. Let t = 2424424244... be the unique fixed point of tau. It is well-known (see, e.g., Lemma 12 in "Morphic words,..."), that t = 2 x_F, where x_F = x_F(4,2) now is the Fibonacci word on the alphabet {4,2}. The partial sums of x_F(4,2) are equal to the generalized Beatty sequence V given by
V(n) = 2*floor(n*phi) + 1,
according to Lemma 8 in the Allouche and Dekking paper.
This proves Kimberling's conjecture, provided we give the sequence A130568 offset 1, as we should.
(End)
LINKS
J.-P. Allouche, F. M. Dekking, Generalized Beatty sequences and complementary triples, Moscow Journal of Combinatorics and Number Theory 8, 325-341 (2019).
M. Dekking, Morphic words, Beatty sequences and integer images of the Fibonacci language, Theoretical Computer Science 809, 407-417 (2020).
EXAMPLE
As a word, A003849 = 01001010010010100..., and replacing each 00 by 2 gives 012101212101210...
MATHEMATICA
s = Nest[Flatten[# /. {0 -> {0, 1}, 1 -> {0}}] &, {0}, 13] (* A003849 *)
w = StringJoin[Map[ToString, s]]
w1 = StringReplace[w, {"00" -> "2"}]
st = ToCharacterCode[w1] - 48 (* A284620 *)
Flatten[Position[st, 0]] (* A284621 *)
Flatten[Position[st, 1]] (* A005843 - conjectured *)
Flatten[Position[st, 2]] (* A130568 - conjectured *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, May 02 2017
STATUS
approved
A287773 {0->010, 1->101}-transform of the infinite Fibonacci word A003849. +20
5
0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET
1
LINKS
FORMULA
a(n) = 1 - A287795(n) for n >= 1.
EXAMPLE
As a word, A003849 = 0100101001001010010100100..., and replacing each 0 by 010 and each 1 by 101 gives 01010101001010101010101001010101001...
MATHEMATICA
s = Nest[Flatten[# /. {0 -> {0, 1}, 1 -> {0}}] &, {0}, 10] (* A003849 *)
w = StringJoin[Map[ToString, s]]
w1 = StringReplace[w, {"0" -> "010", "1" -> "101"}]
st = ToCharacterCode[w1] - 48 (* A287773 *)
Flatten[Position[st, 0]] (* A287774 *)
Flatten[Position[st, 1]] (* A287777 *)
CROSSREFS
Cf. A287774, A287777; A287795 (binary complement).
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jun 03 2017
STATUS
approved
A339824 Even bisection of the infinite Fibonacci word A003849. +20
5
0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET
0
LINKS
FORMULA
a(n) = 2 - [(2n+2)r] + [(2n+1)r], where [ ] = floor and r = golden ratio (A001622).
EXAMPLE
A003849 = (0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, ...), so that
A339824 = (0, 0, 1, 1, 0, 0, 1, ...), the even bisection, and
A339825 = (1, 0, 0, 0, 1, 0, 0, ...), the odd bisection.
MATHEMATICA
r = (1 + Sqrt[5])/2; z = 300;
f[n_] := 2 - Floor[(n + 2) r] + Floor[(n + 1) r]; (* A003849 *)
Table[2 - Floor[(2 n + 2) r] + Floor[(2 n + 1) r], {n, 0, Floor[z/2]}](* A339824 *)
Table[2 - Floor[(2 n + 3) r] + Floor[(2 n + 2) r], {n, 0, Floor[z/2]}](* A339825 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Dec 19 2020
EXTENSIONS
Corrected by Michel Dekking, Feb 23 2021
STATUS
approved
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