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A052658 E.g.f. (1-x^2)*(1-x)/(1-2x-x^2+x^3). 1
1, 1, 4, 30, 264, 3000, 40320, 635040, 11410560, 230791680, 5185555200, 128172844800, 3455996544000, 100952461209600, 3175730791833600, 107037070043904000, 3848161361780736000, 146994587721805824000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..200

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 605

FORMULA

E.g.f.: (-1+x^2)*(-1+x)/(x^3-x^2-2*x+1)

Recurrence: {a(1)=1, a(0)=1, a(2)=4, (n^3+6*n^2+11*n+6)*a(n)+(-n^2-5*n-6)*a(n+1)+(-2*n-6)*a(n+2)+a(n+3)=0, a(3)=30}

Sum(-1/7*(_alpha+_alpha^2-2)*_alpha^(-1-n), _alpha=RootOf(_Z^3-_Z^2-2*_Z+1))*n!

MAPLE

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

MATHEMATICA

With[{nn=20}, CoefficientList[Series[((1-x^2)(1-x))/(1-2x-x^2+x^3), {x, 0, nn}], x]Range[0, nn]!] Harvey P. Dale, May 16 2012

CROSSREFS

Sequence in context: A201200 A102307 A209441 * A220442 A215698 A179540

Adjacent sequences:  A052655 A052656 A052657 * A052659 A052660 A052661

KEYWORD

easy,nonn

AUTHOR

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

STATUS

approved

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Last modified February 18 06:21 EST 2019. Contains 320245 sequences. (Running on oeis4.)