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

Author

Marks R. Nester

Keywords

• nonn

Examples

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

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

Crossrefs

Column 4 of A327878.

Cf. A056465, A056490.

Formula

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

Extensions

Terms corrected by Andrew Howroyd, Sep 28 2019