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Search: id:A000776
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| A000776 |
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n! * (1 + 2*Sum[k=1...n, 1/k]). |
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+0
1
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| 1, 3, 8, 28, 124, 668, 4248, 31176, 259488, 2416032, 24886080, 281004480, 3451887360, 45832538880, 654109585920, 9986000371200, 162391354675200, 2802498609254400, 51156349822771200, 984775394044108800
(list; graph; listen)
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OFFSET
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1,2
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REFERENCES
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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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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 140
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FORMULA
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E.g.f.: 1/(1-x) + ln(1-x)^2.
[ correct e.g.f. is: ] E.g.f.: ln(1-x)*(ln(1-x)-1). [From Vladeta Jovovic (vladeta(AT)eunet.rs), Nov 19 2009]
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CROSSREFS
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Similar to A000774.
Sequence in context: A093356 A135583 A009437 this_sequence A000239 A060707 A080874
Adjacent sequences: A000773 A000774 A000775 this_sequence A000777 A000778 A000779
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KEYWORD
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nonn,new
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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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Incorrect formula deleted Mark van Hoeij (hoeij(AT)math.fsu.edu), Nov 11 2009
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