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Search: id:A052791
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| 0, 0, 0, 6, 72, 540, 3240, 17010, 81648, 367416, 1574640, 6495390, 25981560, 101328084, 386889048, 1450833930, 5356925280, 19514513520, 70252248672, 250273635894, 883318714920
(list; graph; listen)
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OFFSET
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0,4
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 748
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FORMULA
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E.g.f.: x^3*exp(x)^3
Recurrence: {a(1)=0, a(2)=0, a(3)=6, (-3*n-3)*a(n)+(-2+n)*a(n+1)}
0
3^(n-3)*n(n-1)(n-2).
a(n) = n!*sum(i+j+k=n, ijk/(i!j!k!)) - Benoit Cloitre (benoit7848c(AT)orange.fr), Nov 11 2004
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MAPLE
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spec := [S, {B=Set(Z), S=Prod(Z, Z, Z, B, B, B)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
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Sequence in context: A005981 A024272 A052615 this_sequence A129532 A151719 A118313
Adjacent sequences: A052788 A052789 A052790 this_sequence A052792 A052793 A052794
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KEYWORD
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easy,nonn
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AUTHOR
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encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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