A052648 - OEIS
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
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 *)
AUTHOR
encyclopedia(AT)pommard.inria.fr, Jan 25 2000