A056500 Number of primitive (period n) periodic palindromes using exactly four different symbols.

0, 0, 0, 0, 0, 12, 24, 132, 240, 900, 1560, 4968, 8400, 24588, 40824, 113520, 186480, 502248, 818520, 2157360, 3497976, 9085452, 14676024, 37723260, 60780720, 155082900, 249401640, 632947728, 1016542800, 2569816476, 4123173624, 10393520640

Offset

1,6

References

M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia. [See A056391 for pdf file of Chap. 2]

Links

Andrew Howroyd, Table of n, a(n) for n = 1..200

Formula

a(n) = Sum_{d|n} mu(d)*A056490(n/d).

Example

For example, aaabbb is not a (finite) palindrome but it is a periodic palindrome.

Crossrefs

Column 4 of A327878.

Cf. A056465, A056490.

Sequence in context: A051385 A290304 A289335 * A056490 A130163 A002167

Adjacent sequences: A056497 A056498 A056499 * A056501 A056502 A056503

Keyword

nonn

Author

Marks R. Nester

Extensions

Terms corrected by Andrew Howroyd, Sep 28 2019

Status

approved