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Expansion of (1-x)/(1-x-4x^2+2x^3).
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%I #15 Apr 18 2017 07:04:19

%S 1,0,4,2,18,18,86,122,430,746,2222,4346,11742,24682,62958,138202,

%T 340670,767562,1853838,4242746,10122974,23386282,55392686,128691866,

%U 303490046,707472138,1664048590,3886957050,9128207134,21347938154

%N Expansion of (1-x)/(1-x-4x^2+2x^3).

%H INRIA Algorithms Project, <a href="http://ecs.inria.fr/services/structure?nbr=1038">Encyclopedia of Combinatorial Structures 1038</a>

%H <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (1,4,-2)

%F G.f.: -(-1+x)/(1-x-4*x^2+2*x^3)

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

%F Sum(-1/79*(-1-36*_alpha+15*_alpha^2)*_alpha^(-1-n), _alpha=RootOf(1-_Z-4*_Z^2+2*_Z^3))

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

%K easy,nonn

%O 0,3

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

%E More terms from _James A. Sellers_, Jun 06 2000