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A056500 Number of primitive (period n) periodic palindromes using exactly four different symbols. 2
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified April 9 20:55 EDT 2020. Contains 333363 sequences. (Running on oeis4.)