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Search: id:A002867
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| A002867 |
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C(n,[n/2])*(n+1)!.
(Formerly M2035 N0806)
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+0
3
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| 1, 2, 12, 72, 720, 7200, 100800, 1411200, 25401600, 457228800, 10059033600, 221298739200, 5753767219200, 149597947699200, 4487938430976000, 134638152929280000, 4577697199595520000, 155641704786247680000
(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).
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
T. S. Motzkin, Sorting numbers ...: for a link to this paper see A000262.
T. S. Motzkin, Sorting numbers for cylinders and other classification numbers, in Combinatorics, Proc. Symp. Pure Math. 19, AMS, 1971, pp. 167-176.
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FORMULA
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E.g.f.: 1/(sqrt(1+2x)*(1-2x)^(3/2))=1/(sqrt(1-4x^2)*(1-2x)); - Paul Barry (pbarry(AT)wit.ie), Jul 22 2005
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CROSSREFS
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2^n * A000246(n+1).
Sequence in context: A052833 A144086 A005443 this_sequence A130426 A002397 A163085
Adjacent sequences: A002864 A002865 A002866 this_sequence A002868 A002869 A002870
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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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More terms from James A. Sellers (sellersj(AT)math.psu.edu), Jul 10 2000
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