OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..5000
B. Cloitre, N. J. A. Sloane and M. J. Vandermast, Numerical analogues of Aronson's sequence, J. Integer Seqs., Vol. 6 (2003), #03.2.2.
B. Cloitre, N. J. A. Sloane and M. J. Vandermast, Numerical analogues of Aronson's sequence, arXiv:math/0305308 [math.NT], 2003.
FORMULA
a(n) = floor(n*r + 1/(1+r)) where r = 1+sqrt(2).
MATHEMATICA
a[1] = 2;
a[n_] := a[n] = If[MemberQ[Array[a, n-1], n], a[n-1] + 3, a[n-1] + 2];
Array[a, 60] (* Jean-François Alcover, Oct 01 2018 *)
Table[Floor[n (1 + Sqrt[2]) + 1 / (1 + (1 + Sqrt[2]))], {n, 60}] (* Vincenzo Librandi, Oct 02 2018 *)
PROG
(PARI) a(n) = my(r=sqrt(2)+1); (r*(r+1)*n+1)\(r+1); \\ Altug Alkan, Oct 01 2018
(Magma) [Floor(n*(1+Sqrt(2)) + 1/(1+(1+Sqrt(2)))): n in [1..60]]; // Vincenzo Librandi, Oct 02 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Mar 23 2003
STATUS
approved