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A056517
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Number of primitive (period n) periodic palindromic structures using a maximum of six different symbols.
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3
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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
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OFFSET
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0,5
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COMMENTS
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For example, aaabbb is not a (finite) palindrome but it is a periodic palindrome.
Permuting the symbols will not change the structure.
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REFERENCES
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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]
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LINKS
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FORMULA
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a(n) = Sum_{d|n} mu(d)*A056507(n/d) for n > 0.
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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a(0)=1 prepended and terms a(16) and beyond from Andrew Howroyd, Oct 01 2019
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STATUS
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approved
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