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A052681 Expansion of e.g.f. (1-x)/(1 - x - x^2 - 2*x^3 + 2*x^4). 1
1, 0, 2, 18, 48, 840, 9360, 90720, 1653120, 25764480, 442713600, 9540115200, 201659673600, 4744989849600, 123531638630400, 3325415917824000, 97123590660096000, 3021564701675520000, 98526128957448192000 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
LINKS
FORMULA
E.g.f.: (1-x)/(1 - x - x^2 - 2*x^3 + 2*x^4).
Recurrence: a(0)=1, a(1)=0, a(2)=2, a(3)=18, a(n+4) = (n+4)*a(n+3) + (12 + 7*n + n^2)*a(n+2) + (48 + 52*n + 18*n^2 + 2*n^3)*a(n+1) - 2*(n^4 + 10*n^3 + 35*n^2 + 50*n + 24)*a(n).
a(n) = (n!/353)*Sum_{alpha=RootOf(1 - Z - z^2 - 2*Z^3 + 2*Z^4)} (18 + 106*alpha - 33*alpha^2 - 28*alpha^3)*alpha^(-1-n).
a(n) = n!*A052546(n). - R. J. Mathar, Nov 27 2011
MAPLE
spec := [S, {S=Sequence(Prod(Z, Z, Union(Z, Z, Sequence(Z))))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
MATHEMATICA
With[{nn=20}, CoefficientList[Series[(1-x)/(1-x-x^2-2x^3+2x^4), {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, May 23 2014 *)
PROG
(Magma) R<x>:=PowerSeriesRing(Rationals(), 40); Coefficients(R!(Laplace( (1-x)/(1-x-x^2-2*x^3+2*x^4) ))); // G. C. Greubel, Jun 09 2022
(SageMath)
def A052681_list(prec):
P.<x> = PowerSeriesRing(QQ, prec)
return P( (1-x)/(1-x-x^2-2*x^3+2*x^4) ).egf_to_ogf().list()
A052681_list(40) # G. C. Greubel, Jun 09 2022
CROSSREFS
Sequence in context: A304933 A126909 A139268 * A208652 A223469 A048910
KEYWORD
easy,nonn
AUTHOR
encyclopedia(AT)pommard.inria.fr, Jan 25 2000
STATUS
approved

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Last modified March 29 04:23 EDT 2024. Contains 371264 sequences. (Running on oeis4.)