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A052900 Expansion of (1-x)/(1-x-3x^3). 1
1, 0, 0, 3, 3, 3, 12, 21, 30, 66, 129, 219, 417, 804, 1461, 2712, 5124, 9507, 17643, 33015, 61536, 114465, 213510, 398118, 741513, 1382043, 2576397, 4800936, 8947065, 16676256, 31079064, 57920259, 107949027, 201186219, 374946996 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..34.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 876

FORMULA

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

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

Sum(-1/85*(2+9*_alpha^2-29*_alpha)*_alpha^(-1-n), _alpha=RootOf(-1+_Z+3*_Z^3))

MAPLE

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

CROSSREFS

a(n) = 3*A084386(n-3), also first differences of A084386.

Sequence in context: A225073 A152575 A170851 * A024947 A291407 A147823

Adjacent sequences:  A052897 A052898 A052899 * A052901 A052902 A052903

KEYWORD

easy,nonn

AUTHOR

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

EXTENSIONS

More terms from James A. Sellers, Jun 06 2000

STATUS

approved

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Last modified October 23 17:32 EDT 2019. Contains 328373 sequences. (Running on oeis4.)