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A052784
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A simple grammar.
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0
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0, 0, 0, 0, 0, 0, 720, 7560, 50400, 272160, 1300320, 5738040, 23958000, 96061680, 373477104, 1417295880, 5274360000, 19313985600, 69770966976, 249130574424, 880629138000
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,7
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LINKS
| INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 741
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FORMULA
| E.g.f.: x^3*exp(x)^3-3*x^3*exp(x)^2+3*x^3*exp(x)-x^3
Recurrence: {a(1)=0, a(2)=0, a(4)=0, a(3)=0, a(5)=0, a(6)=720, (-36*n^2-66*n-6*n^3-36)*a(n)+(-44*n+11*n^3+33*n^2-132)*a(n+1)+(-6*n^3-36+42*n)*a(n+2)+(-3*n^2+n^3+2*n)*a(n+3)}
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MAPLE
| spec := [S, {B=Set(Z, 1 <= card), S=Prod(Z, Z, Z, B, B, B)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
| Sequence in context: A153760 A029574 A119540 * A052786 A187192 A052792
Adjacent sequences: A052781 A052782 A052783 * A052785 A052786 A052787
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KEYWORD
| easy,nonn
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AUTHOR
| encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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