A285042 Number of primitive (period n) periodic palindromic structures of length n using an infinite alphabet.

1, 1, 1, 1, 3, 4, 10, 14, 36, 50, 138, 202, 562, 876, 2589, 4134, 12828, 21146, 69115, 115974, 398619, 678554, 2450202, 4213596, 15939338, 27644432, 109304036, 190899270, 787013630, 1382958544, 5931819804, 10480142146, 46673246440, 82864869600, 382473261356

Offset: 0

Author

Andrew Howroyd, Apr 08 2017

Keywords

• nonn

Comments

See A285037 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 A285037.

Cf. A285013.

Programs

PARI

\\ Requires T from A285037.
seq(n)={my(A=T(n)); concat([1], vector(n, i, vecsum(A[i, ])))} \\ Andrew Howroyd, Oct 02 2019

Formula

a(n) = Sum_{d | n} mu(n/d) * A285013(d) for n > 0.

Extensions

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