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A052793 A simple grammar. 0
0, 0, 0, 0, 0, 0, 720, 5040, 23520, 90720, 312480, 997920, 3017520, 8751600, 24552528, 67026960, 178825920, 467812800, 1203094080, 3048024384, 7620293520 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,7

LINKS

Table of n, a(n) for n=0..20.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 750

FORMULA

E.g.f.: x^4*exp(x)^2-2*x^4*exp(x)+x^4

Recurrence: {a(1)=0, a(2)=0, a(4)=0, a(3)=0, a(5)=0, a(6)=720, (2*n^2+6*n+4)*a(n)+(18-3*n^2+3*n)*a(n+1)+(n^2-5*n+6)*a(n+2)}

MAPLE

spec := [S, {B=Set(Z, 1 <= card), S=Prod(Z, Z, Z, Z, B, B)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);

CROSSREFS

Sequence in context: A187290 A218487 A053625 * A179728 A052799 A229569

Adjacent sequences:  A052790 A052791 A052792 * A052794 A052795 A052796

KEYWORD

easy,nonn

AUTHOR

encyclopedia(AT)pommard.inria.fr, Jan 25 2000

STATUS

approved

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Last modified October 25 09:51 EDT 2021. Contains 348239 sequences. (Running on oeis4.)