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A052659 Expansion of 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
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
Cf. A007070.
Sequence in context: A005797 A233835 A300993 * A346684 A350264 A113376
KEYWORD
easy,nonn
AUTHOR
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
STATUS
approved

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Last modified April 23 07:16 EDT 2024. Contains 371905 sequences. (Running on oeis4.)