A052876 Expansion of e.g.f. (exp(x)-1)^2/(-2+exp(x))^2.
0, 0, 2, 18, 158, 1530, 16622, 201978, 2724878, 40492890, 657944942, 11611834938, 221291822798, 4530383962650, 99179581033262, 2312402554523898, 57211901491595918, 1497211181084718810
Offset: 0
Links
- INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 847
Programs
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Maple
spec := [S,{B=Set(Z,1 <= card),C=Sequence(B,1 <= card),S=Prod(C,C)},labeled]: seq(combstruct[count](spec,size=n), n=0..20); -
Mathematica
With[{nn=20},CoefficientList[Series[((Exp[x]-1)^2/(Exp[x]-2)^2),{x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, Jul 19 2018 *)
Formula
Extensions
Name changed by Wesley Ivan Hurt, Jun 26 2022
Comments