A279625 Number of ternary palindromes of length 2n+1 having no (7/4)+ powers.

3, 6, 6, 12, 12, 6, 6, 6, 6, 6, 12, 12, 18, 30, 30, 36, 54, 66, 72, 90, 96, 114, 168, 210, 252, 330, 414, 486, 618, 756, 888, 1200, 1494, 1776, 2232, 2796, 3456, 4362, 5454, 6660, 8454, 10530, 12924, 16116, 20232, 25272, 31446, 39150, 48408, 60438

Offset

0,1

Comments

A (7/4)+ power is a word of the form xx', where x' is a prefix of x and |x'| > (3/4)|x|. Every odd length (2n+1) is guaranteed to have at least one such palindrome.

Links

Table of n, a(n) for n=0..49.

Example

For n = 7 there are 6 palindromes of length 15 satisfying the conditions: {010201202102010, 020102101201020, 101210212012101, 121012010210121, 202120121021202, 212021020120212}.

Crossrefs

Cf. A279611.

Sequence in context: A287882 A066297 A160713 * A012212 A232941 A080866

Adjacent sequences: A279622 A279623 A279624 * A279626 A279627 A279628

Keyword

nonn

Author

Jeffrey Shallit, Dec 16 2016

Status

approved