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Search: id:A007289
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| A007289 |
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Number of alternating 3-signed permutations.
(Formerly M1873)
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+0
2
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| 1, 2, 8, 46, 352, 3362, 38528, 515086, 7869952, 135274562, 2583554048, 54276473326, 1243925143552, 30884386347362, 825787662368768, 23657073914466766, 722906928498737152, 23471059057478981762
(list; graph; listen)
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OFFSET
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0,2
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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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FORMULA
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G.f.: ( sin 2x + cos x) / cos 3x.
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CROSSREFS
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Sequence in context: A128085 A052801 A074599 this_sequence A099765 A096656 A102009
Adjacent sequences: A007286 A007287 A007288 this_sequence A007290 A007291 A007292
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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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