A056499 Number of primitive (period n) periodic palindromes using exactly three different symbols.

0, 0, 0, 3, 6, 21, 36, 90, 150, 339, 540, 1149, 1806, 3765, 5790, 11880, 18150, 36894, 55980, 113145, 170970, 344541, 519156, 1043190, 1569744, 3149979, 4733670, 9488409, 14250606, 28544205, 42850116, 85786560, 128746410, 257672355, 386634018, 773623116, 1160688606

Offset: 1

Author

Marks R. Nester

Keywords

• nonn

Comments

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 3 of A327878.

Cf. A056464, A056489.

Formula

a(n) = Sum_{d|n} mu(d)*A056489(n/d).

Extensions

Terms a(32) and beyond from Andrew Howroyd, Sep 28 2019