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A285013 Number of periodic palindromic structures of length n using an infinite alphabet. 3
1, 1, 2, 2, 5, 5, 13, 15, 41, 52, 144, 203, 578, 877, 2605, 4140, 12869, 21147, 69178, 115975, 398766, 678570, 2450406, 4213597, 15939952, 27644437, 109304914, 190899322, 787016238, 1382958545, 5931824093, 10480142147, 46673259309, 82864869804, 382473282504 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

See A285012 for additional information. Permuting the symbols will not change the structure.

LINKS

Andrew Howroyd, Table of n, a(n) for n = 0..500

PROG

(PARI) \\ Requires T from A285012.

seq(n)={my(A=T(n)); concat([1], vector(n, i, vecsum(A[i, ])))} \\ Andrew Howroyd, Oct 02 2019

CROSSREFS

Row sums of A285012.

Cf. A165137, A284841, A285042.

Sequence in context: A056505 A056506 A056507 * A095014 A129996 A208355

Adjacent sequences:  A285010 A285011 A285012 * A285014 A285015 A285016

KEYWORD

nonn

AUTHOR

Andrew Howroyd, Apr 07 2017

EXTENSIONS

a(0)=1 prepended and terms a(28) and beyond from Andrew Howroyd, Oct 02 2019

STATUS

approved

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Last modified October 1 01:28 EDT 2022. Contains 357134 sequences. (Running on oeis4.)