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A000775
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n! * (n + 1 + 2*Sum[k=1...n, 1/k]).
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0
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1, 4, 12, 46, 220, 1268, 8568, 66456, 582048, 5681952, 61174080, 720089280, 9199906560, 126783809280, 1874605662720, 29601115891200, 497155992883200, 8849184886886400, 166399076525875200, 3296032301811916800
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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REFERENCES
| 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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FORMULA
| E.g.f.: x/(1-x)+ln(1-x)^2. - Vladeta Jovovic (vladeta(AT)eunet.rs), Feb 02 2003
a(0)=1, a(n+1)=(n+1)*a(n)+(n+3)*n! for n>0. Sean A. Irvine, Jun 10 2011
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CROSSREFS
| Similar to A000774.
Sequence in context: A149373 A151464 A101225 * A149374 A149375 A035310
Adjacent sequences: A000772 A000773 A000774 * A000776 A000777 A000778
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| Incorrect formula deleted Mark (hoeij(AT)math.fsu.edu), Nov 11 2009
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