Expansion of e.g.f. x^4*exp(x)^2.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =24a(5) =240a(6) =1440a(7) =6720a(8) =26880a(9) =96768a(10) =322560a(11) =1013760a(12) =3041280a(13) =8785920a(14) =24600576a(15) =67092480a(16) =178913280a(17) =467927040a(18) =1203240960a(19) =3048210432a(20) =7620526080a(21) =18827182080a(22) =46022000640a(23) =111421685760a(24) =267412045824a(25) =636695347200