

A052973


Expansion of ( 1x ) / ( 1x3*x^2+x^3 ).


3



1, 0, 3, 2, 11, 14, 45, 76, 197, 380, 895, 1838, 4143, 8762, 19353, 41496, 90793, 195928, 426811, 923802, 2008307, 4352902, 9454021, 20504420, 44513581, 96572820, 209609143, 454814022, 987068631, 2141901554, 4648293425
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OFFSET

0,3


LINKS

Table of n, a(n) for n=0..30.
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 1045
Index to sequences with linear recurrences with constant coefficients, signature (1,3,1).


FORMULA

G.f.: (1+x)/(1x3*x^2+x^3)
Recurrence: {a(1)=0, a(0)=1, a(2)=3, a(n)3*a(n+1)a(n+2)+a(n+3)=0}
Sum(1/74*(134*_alpha+9*_alpha^2)*_alpha^(1n), _alpha=RootOf(1_Z3*_Z^2+_Z^3))


MAPLE

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


CROSSREFS

Sequence in context: A134426 A122672 A194608 * A087956 A116391 A087629
Adjacent sequences: A052970 A052971 A052972 * A052974 A052975 A052976


KEYWORD

easy,nonn


AUTHOR

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


EXTENSIONS

More terms from James A. Sellers, Jun 06 2000


STATUS

approved



