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A056429
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Number of step cyclic shifted sequence structures using a maximum of two different symbols.
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4
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1, 2, 2, 4, 3, 8, 5, 14, 11, 26, 15, 88, 37, 130, 184, 357, 261, 1346, 805, 3760, 4434, 9758, 8385, 47462, 33781, 108330, 138767, 408376, 331185, 2251816, 1155735
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OFFSET
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1,2
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COMMENTS
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See A056371 for an explanation of step shifts. Under step cyclic shifts, abcde, bdace, bcdea, cdeab and daceb etc. are equivalent. 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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Table of n, a(n) for n=1..31.
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FORMULA
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Use de Bruijn's generalization of Polya's enumeration theorem as discussed in reference.
a(n) = A288627(n, 2) + 1. - Andrew Howroyd, Jun 13 2017
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CROSSREFS
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Cf. A002729, A288627.
Sequence in context: A285620 A185959 A006799 * A133806 A283717 A185333
Adjacent sequences: A056426 A056427 A056428 * A056430 A056431 A056432
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KEYWORD
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nonn
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AUTHOR
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Marks R. Nester
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STATUS
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approved
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