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A052698 E.g.f. x/((1-x)(1-3x)). 0
0, 1, 8, 78, 960, 14520, 262080, 5508720, 132249600, 3571102080, 107136691200, 3535550726400, 127280305152000, 4963938127948800, 208485488552140800, 9381848292520704000, 450328738963783680000, 22966766042840395776000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..17.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 648

FORMULA

E.g.f.: x/(-1+x)/(-1+3*x)

Recurrence: {a(1)=1, a(0)=0, (3*n^2+9*n+6)*a(n)+(-4*n-8)*a(n+1)+a(n+2)=0}

(-1/2+1/2*3^n)*n!

a(n) = n!*A003462(n). - R. J. Mathar, Nov 27 2011

MAPLE

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

MATHEMATICA

With[{nn=20}, CoefficientList[Series[x/((1-x)(1-3x)), {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, Nov 05 2014 *)

CROSSREFS

Sequence in context: A132164 A058480 A000435 * A052603 A071556 A316203

Adjacent sequences:  A052695 A052696 A052697 * A052699 A052700 A052701

KEYWORD

easy,nonn

AUTHOR

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

STATUS

approved

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Last modified October 16 00:50 EDT 2018. Contains 316252 sequences. (Running on oeis4.)