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A056515 Number of primitive (period n) periodic palindromic structures using a maximum of four different symbols. 5
1, 1, 1, 1, 3, 4, 10, 14, 35, 49, 127, 186, 463, 714, 1799, 2789, 6996, 11050, 27685, 43946, 109925, 175259, 438495, 700074, 1750445, 2798246, 6996927, 11188856, 27973533, 44747434, 111873782, 178973354, 447438656, 715860463, 1789673215, 2863377048, 7158463662 (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)*A056505(n/d) for n > 0.

Moebius transform of A056505.

a(n) = Sum_{k=1..4} A285037(n, k) for n > 0. - Andrew Howroyd, Oct 01 2019

CROSSREFS

Cf. A056478, A056505, A285037.

Sequence in context: A106523 A007068 A121720 * A056516 A056517 A285042

Adjacent sequences:  A056512 A056513 A056514 * A056516 A056517 A056518

KEYWORD

nonn

AUTHOR

Marks R. Nester

EXTENSIONS

a(0)=1 prepended and terms a(17) and beyond from Andrew Howroyd, Oct 01 2019

STATUS

approved

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Last modified February 19 22:04 EST 2020. Contains 332060 sequences. (Running on oeis4.)