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A052648 Expansion of e.g.f. 5*x/(1-x). 2
0, 5, 10, 30, 120, 600, 3600, 25200, 201600, 1814400, 18144000, 199584000, 2395008000, 31135104000, 435891456000, 6538371840000, 104613949440000, 1778437140480000, 32011868528640000, 608225502044160000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..19.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 595

Luis Manuel Rivera, Integer sequences and k-commuting permutations, arXiv preprint arXiv:1406.3081 [math.CO], 2014-2015.

FORMULA

E.g.f.: 5*x/(1-x)

Recurrence: {a(0)=0, (-1-n)*a(n)+a(n+1)=0, a(1)=5}

a(n) = 5*n!, n>0.

MAPLE

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

MATHEMATICA

With[{nn=20}, CoefficientList[Series[(5x)/(1-x), {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, May 01 2016 *)

CROSSREFS

Cf. A000142, A052849 (k=2), A052560 (k=3), A052578 (k=4).

Sequence in context: A189315 A056422 A032296 * A020995 A174467 A005201

Adjacent sequences:  A052645 A052646 A052647 * A052649 A052650 A052651

KEYWORD

easy,nonn

AUTHOR

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

STATUS

approved

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Last modified August 24 03:20 EDT 2019. Contains 326260 sequences. (Running on oeis4.)