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%I #11 Jun 03 2022 18:14:36
%S 0,0,0,0,0,0,720,5040,23520,90720,312480,997920,3017520,8751600,
%T 24552528,67026960,178825920,467812800,1203094080,3048024384,
%U 7620293520
%N A simple grammar.
%H INRIA Algorithms Project, <a href="http://ecs.inria.fr/services/structure?nbr=750">Encyclopedia of Combinatorial Structures 750</a>
%F E.g.f.: x^4*exp(x)^2-2*x^4*exp(x)+x^4
%F D-finite 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)=0}
%p 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);
%K easy,nonn
%O 0,7
%A encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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