A285013 Number of periodic palindromic structures of length n using an infinite alphabet.

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

Offset: 0

Author

Andrew Howroyd, Apr 07 2017

Keywords

• nonn

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

Crossrefs

Row sums of A285012.

Cf. A165137, A284841, A285042.

Programs

PARI

\\ Requires T from A285012.
seq(n)={my(A=T(n)); concat([1], vector(n, i, vecsum(A[i,])))} \\ Andrew Howroyd, Oct 02 2019

Extensions

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