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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
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
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
KEYWORD
nonn
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