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A006873
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Number of alternating 4-signed permutations.
(Formerly M4430)
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1
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1, 1, 7, 47, 497, 6241, 95767, 1704527, 34741217, 796079041, 20273087527, 567864586607, 17352768515537, 574448847467041, 20479521468959287, 782259922208550287
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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REFERENCES
| Richard Ehrenborg and Margaret A. Readdy, Sheffer posets and r-signed permutations, Annales des Sciences Math\'ematiques du Qu\'ebec {\bf 19} (1995), 173-196.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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CROSSREFS
| Sequence in context: A093173 A173772 A178002 * A015097 A201176 A013400
Adjacent sequences: A006870 A006871 A006872 * A006874 A006875 A006876
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Simon Plouffe (simon.plouffe(AT)gmail.com)
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