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A052970
Expansion of (1-2x)/(1-2x-2x^2+2x^3).
1
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
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
KEYWORD
easy,nonn
AUTHOR
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
EXTENSIONS
More terms from James A. Sellers, Jun 05 2000
STATUS
approved