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A056514
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Number of primitive (period n) periodic palindromic structures using a maximum of three different symbols.
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5
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1, 1, 1, 1, 3, 4, 9, 13, 28, 39, 84, 121, 244, 364, 741, 1088, 2200, 3280, 6591, 9841, 19720, 29510, 59169, 88573, 177240, 265716, 531804, 797121, 1594684, 2391484, 4783968, 7174453, 14350000, 21523238, 43050000, 64570064, 129143196, 193710244, 387430329, 581130368, 1162271280
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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)*A056504(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(36) and beyond from Andrew Howroyd, Oct 01 2019
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STATUS
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approved
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