E.g.f.: x^2*(exp(x)-1)^3.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =120a(6) =1080a(7) =6300a(8) =30240a(9) =130032a(10) =521640a(11) =1996500a(12) =7389360a(13) =26676936a(14) =94486392a(15) =329647500a(16) =1136116800a(17) =3876164832a(18) =13112135496a(19) =44031456900a(20) =146920942800a(21) =487489214520