A052970 Expansion of (1-2x)/(1-2x-2x^2+2x^3).

1, 0, 2, 2, 8, 16, 44, 104, 264, 648, 1616, 4000, 9936, 24640, 61152, 151712, 376448, 934016, 2317504, 5750144, 14267264, 35399808, 87833856, 217932800, 540733696, 1341665280, 3328932352, 8259727872, 20493989888, 50849570816, 126167665664

Offset

0,3

Links

Table of n, a(n) for n=0..30.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 1042

Index entries for linear recurrences with constant coefficients, signature (2,2,-2).

Formula

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

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

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

Maple

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

Crossrefs

Sequence in context: A276054 A192305 A228797 * A220589 A109190 A016120

Adjacent sequences: A052967 A052968 A052969 * A052971 A052972 A052973

Keyword

easy,nonn

Author

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

Extensions

More terms from James A. Sellers, Jun 05 2000

Status

approved