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A279626 Number of palindromes over an alphabet of size 4 of length 2n+1 having no (3/2)+ powers. 0
4, 12, 24, 48, 120, 240, 480, 1104, 2448, 5376, 12048, 27456, 61704, 140664 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

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

LINKS

Table of n, a(n) for n=0..13.

EXAMPLE

For n = 2 the possibilities are {01210, 01310, 02120, 02320, 03130, 03230} and their images under permutations of the alphabet.

CROSSREFS

Cf. A279611, A279625.

Sequence in context: A132477 A102651 A102652 * A238607 A143270 A037338

Adjacent sequences:  A279623 A279624 A279625 * A279627 A279628 A279629

KEYWORD

nonn

AUTHOR

Jeffrey Shallit, Dec 16 2016

STATUS

approved

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Last modified April 24 00:02 EDT 2019. Contains 322404 sequences. (Running on oeis4.)