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A056473
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Number of palindromic structures using exactly four different symbols.
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1
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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; refs; listen; history; internal format)
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OFFSET
| 1,9
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COMMENTS
| Permuting the symbols will not change the structure.
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REFERENCES
| M. R. Nester (1999). Mathematical investigations of some plant interaction designs. PhD Thesis. University of Queensland, Brisbane, Australia.
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FORMULA
| stirling2( [(n+1)/2], 4).
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CROSSREFS
| Cf. A000453, A007581.
Sequence in context: A111220 A106789 A056483 * A165831 A102377 A038312
Adjacent sequences: A056470 A056471 A056472 * A056474 A056475 A056476
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KEYWORD
| nonn
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AUTHOR
| Marks R. Nester (nesterm(AT)dpi.qld.gov.au)
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