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Search: id:A056473
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| A056473 |
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Number of palindromic structures using exactly four different symbols. |
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+0
2
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| 0, 0, 0, 0, 0, 0, 1, 1, 10, 10, 65, 65, 350, 350, 1701, 1701, 7770, 7770, 34105, 34105, 145750, 145750, 611501, 611501, 2532530, 2532530, 10391745, 10391745, 42355950, 42355950, 171798901
(list; graph; listen)
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OFFSET
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1,9
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COMMENT
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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.
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FORMULA
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stirling2( [(n+1)/2], 4).
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CROSSREFS
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Cf. A000453, A007581.
Sequence in context: A111220 A106789 A056483 this_sequence A102377 A038312 A010100
Adjacent sequences: A056470 A056471 A056472 this_sequence A056474 A056475 A056476
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KEYWORD
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nonn
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AUTHOR
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Marks R. Nester (nesterm(AT)dpi.qld.gov.au)
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