A052970 - OEIS

%I #15 Apr 18 2017 07:04:19

%S 1,0,2,2,8,16,44,104,264,648,1616,4000,9936,24640,61152,151712,376448,

%T 934016,2317504,5750144,14267264,35399808,87833856,217932800,

%U 540733696,1341665280,3328932352,8259727872,20493989888,50849570816,126167665664

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

%H INRIA Algorithms Project, <a href="http://ecs.inria.fr/services/structure?nbr=1042">Encyclopedia of Combinatorial Structures 1042</a>

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

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

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

%F Sum(-1/37*(3-15*_alpha+2*_alpha^2)*_alpha^(-1-n), _alpha=RootOf(2*_Z^3-2*_Z^2-2*_Z+1))

%p spec := [S,{S=Sequence(Prod(Union(Prod(Sequence(Union(Z,Z)),Z),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 05 2000