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A052659 E.g.f. (1-2x)(1-x)/(1-4x+2x^2). 0
1, 1, 8, 84, 1152, 19680, 403200, 9636480, 263208960, 8087869440, 276137164800, 10370703974400, 424893579264000, 18858806481715200, 901431900123955200, 46165215285116928000, 2521886466187984896000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..16.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 606

FORMULA

E.g.f.: (-1+2*x)*(-1+x)/(1-4*x+2*x^2)

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

Sum(-1/4*(-1+2*_alpha)*_alpha^(-1-n), _alpha=RootOf(1-4*_Z+2*_Z^2))*n!

a(n) = n!*A007070(n-1). - R. J. Mathar, Nov 27 2011

MAPLE

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

CROSSREFS

Sequence in context: A005797 A233835 A300993 * A113376 A205311 A258338

Adjacent sequences:  A052656 A052657 A052658 * A052660 A052661 A052662

KEYWORD

easy,nonn

AUTHOR

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

STATUS

approved

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Last modified July 15 00:36 EDT 2020. Contains 335762 sequences. (Running on oeis4.)