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A056517 Number of primitive (period n) periodic palindromic structures using a maximum of six different symbols. 3
1, 1, 1, 1, 3, 4, 10, 14, 36, 50, 138, 202, 561, 875, 2571, 4105, 12548, 20647, 65456, 109298, 356466, 601476, 2005341, 3403126, 11522216, 19628059, 67182654, 114700263, 395494722, 676207627, 2343260789, 4010090462, 13942474064, 23874361996, 83192218842, 142508723632 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

COMMENTS

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

Permuting the symbols will not change the structure.

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 = 0..200

FORMULA

a(n) = Sum_{d|n} mu(d)*A056507(n/d) for n > 0.

a(n) = Sum_{k=1..6} A285037(n, k) for n > 0. - Andrew Howroyd, Oct 01 2019

CROSSREFS

Cf. A056480, A056507, A285037.

Sequence in context: A121720 A056515 A056516 * A285042 A319719 A048155

Adjacent sequences:  A056514 A056515 A056516 * A056518 A056519 A056520

KEYWORD

nonn

AUTHOR

Marks R. Nester

EXTENSIONS

Corrected by T. D. Noe, Oct 25 2006

a(0)=1 prepended and terms a(16) and beyond from Andrew Howroyd, Oct 01 2019

STATUS

approved

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Last modified February 23 14:41 EST 2020. Contains 332163 sequences. (Running on oeis4.)