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A056499 Number of primitive (period n) periodic palindromes using exactly three different symbols. 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

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

FORMULA

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

CROSSREFS

Column 3 of A327878.

Cf. A056464, A056489.

Sequence in context: A050611 A270510 A300891 * A056489 A015649 A297189

Adjacent sequences:  A056496 A056497 A056498 * A056500 A056501 A056502

KEYWORD

nonn

AUTHOR

Marks R. Nester

EXTENSIONS

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

STATUS

approved

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Last modified April 5 20:24 EDT 2020. Contains 333260 sequences. (Running on oeis4.)