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A052587 E.g.f. x^2(1-x)/(1-2x). 0
0, 0, 2, 6, 48, 480, 5760, 80640, 1290240, 23224320, 464486400, 10218700800, 245248819200, 6376469299200, 178541140377600, 5356234211328000, 171399494762496000, 5827582821924864000, 209792981589295104000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Essentially the same as A051578. - R. J. Mathar, Feb 22 2008

LINKS

Table of n, a(n) for n=0..18.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 532

FORMULA

E.g.f.: x^2*(-1+x)/(-1+2*x)

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

1/8*2^n*n!, n>2.

MAPLE

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

CROSSREFS

Sequence in context: A292934 A195203 A052743 * A052735 A052717 A175430

Adjacent sequences:  A052584 A052585 A052586 * A052588 A052589 A052590

KEYWORD

easy,nonn

AUTHOR

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

STATUS

approved

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Last modified October 20 05:42 EDT 2017. Contains 293601 sequences.