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

Terms

a(0) =0a(1) =0a(2) =2a(3) =24a(4) =192a(5) =1280a(6) =7680a(7) =43008a(8) =229376a(9) =1179648a(10) =5898240a(11) =28835840a(12) =138412032a(13) =654311424a(14) =3053453312a(15) =14092861440a(16) =64424509440a(17) =292057776128