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A133799
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a(2) = 1, a(3)=3; for n >= 4, a(n) = (n-2)!*Stirling_2(n,n-1)/2 = n!/4.
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3
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1, 3, 6, 30, 180, 1260, 10080, 90720, 907200, 9979200, 119750400, 1556755200, 21794572800, 326918592000, 5230697472000, 88921857024000, 1600593426432000, 30411275102208000, 608225502044160000, 12772735542927360000, 281000181944401920000
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,2
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MATHEMATICA
| f[n_]:=If[IntegerPart[n]==n, n, Numerator[n]]; a=1; lst={}; Do[a=n*a-a; AppendTo[lst, f[a/4]], {n, 3, 3*4!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), May 28 2009]
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CROSSREFS
| A diagonal of triangle A133800.
Sequence in context: A125521 A090932 A157534 * A088436 A088506 A061137
Adjacent sequences: A133796 A133797 A133798 * A133800 A133801 A133802
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Jan 17 2008
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EXTENSIONS
| Corrected parameters in definition. - Geoffrey Critzer (critzer.geoffrey(AT)usd443.org), Apr 26 2009
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