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A052672 E.g.f. (1-x)/(1-x-2x^2+x^3). 0

%I

%S 1,0,4,6,120,600,10080,95760,1693440,23950080,475372800,8821612800,

%T 199743667200,4533271142400,116906088499200,3112264995840000,

%U 90679371374592000,2757644630028288000,89895729202126848000

%N E.g.f. (1-x)/(1-x-2x^2+x^3).

%H INRIA Algorithms Project, <a href="http://ecs.inria.fr/services/structure?nbr=620">Encyclopedia of Combinatorial Structures 620</a>

%F E.g.f.: -(-1+x)/(x^3-2*x^2-x+1)

%F Recurrence: {a(1)=0, a(0)=1, a(2)=4, (n^3+6*n^2+11*n+6)*a(n)+(-2*n^2-10*n-12)*a(n+1)+(-n-3)*a(n+2)+a(n+3)=0}

%F Sum(-1/7*_alpha*(-3+_alpha)*_alpha^(-1-n), _alpha=RootOf(_Z^3-2*_Z^2-_Z+1))*n!.

%F a(n) = n!*A052547(n). - _R. J. Mathar_, Nov 27 2011

%p spec := [S,{S=Sequence(Prod(Z,Union(Z,Prod(Z,Sequence(Z)))))},labeled]: seq(combstruct[count](spec,size=n), n=0..20);

%K easy,nonn

%O 0,3

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

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Last modified September 27 03:21 EDT 2020. Contains 337380 sequences. (Running on oeis4.)