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Search: id:A006873
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| A006873 |
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Number of alternating 4-signed permutations.
(Formerly M4430)
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+0
2
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| 1, 1, 7, 47, 497, 6241, 95767, 1704527, 34741217, 796079041, 20273087527, 567864586607, 17352768515537, 574448847467041, 20479521468959287, 782259922208550287
(list; graph; listen)
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OFFSET
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0,3
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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.
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CROSSREFS
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Sequence in context: A088057 A108434 A093173 this_sequence A015097 A013400 A013399
Adjacent sequences: A006870 A006871 A006872 this_sequence A006874 A006875 A006876
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Simon Plouffe (simon.plouffe(AT)gmail.com)
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