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Search: id:A006595
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| A006595 |
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(n+2)!/4 + n!/2.
(Formerly M1794)
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+0
2
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| 1, 2, 7, 33, 192, 1320, 10440, 93240, 927360, 10160640, 121564800, 1576713600, 22034073600, 330032102400, 5274286617600, 89575694208000, 1611054821376000, 30589118816256000, 611426688897024000
(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).
L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 258.
J. R. Stembridge, Some combinatorial aspects of reduced words in finite Coxeter groups. Trans. Amer. Math. Soc. 349 (1997), no. 4, 1285-1332.
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CROSSREFS
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A diagonal of A059418.
Sequence in context: A162661 A104981 A058797 this_sequence A059099 A020103 A014623
Adjacent sequences: A006592 A006593 A006594 this_sequence A006596 A006597 A006598
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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Improved description and sequence extended, 8/95.
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