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A056504
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Number of periodic palindromic structures of length n using a maximum of three different symbols.
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5
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1, 1, 2, 2, 5, 5, 12, 14, 33, 41, 90, 122, 259, 365, 756, 1094, 2233, 3281, 6642, 9842, 19813, 29525, 59292, 88574, 177527, 265721, 532170, 797162, 1595443, 2391485, 4785156, 7174454, 14352233, 21523361, 43053282, 64570082, 129150085, 193710245, 387440172, 581130734, 1162291121
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OFFSET
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0,3
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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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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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