A261680 - OEIS

A261680

Number of ordered quadruples (u,v,w,x) of binary palindromes (see A006995) with u+v+w+x=n.

1, 4, 6, 8, 13, 16, 22, 28, 34, 44, 50, 60, 59, 72, 70, 80, 92, 88, 114, 96, 125, 104, 152, 120, 172, 144, 188, 152, 215, 144, 242, 160, 272, 172, 302, 180, 329, 216, 352, 240, 388, 228, 430, 228, 442, 212, 476, 192, 506, 228, 496, 248, 540, 252, 582, 276, 592

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OFFSET

0,2

COMMENTS

Conjecture: a(n)>0: every number is the sum of four binary palindromes. (Compare A261422, A261675.)

LINKS

N. J. A. Sloane, Table of n, a(n) for n = 0..9999

Aayush Rajasekaran, Jeffrey Shallit, and Tim Smith, Sums of Palindromes: an Approach via Nested-Word Automata, preprint arXiv:1706.10206 [cs.FL], June 30 2017.

FORMULA

G.f. = (Sum_{p in A006995} x^p)^4.

CROSSREFS

Cf. A006995, A261422, A261675, A261679.

Sequence in context: A145284 A023560 A340960 * A218465 A359676 A050902

Adjacent sequences: A261677 A261678 A261679 * A261681 A261682 A261683

KEYWORD

nonn,base

AUTHOR

N. J. A. Sloane, Sep 04 2015

STATUS

approved