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

Terms

a(0) =2a(1) =8a(2) =38a(3) =212a(4) =1370a(5) =10112a(6) =84158a(7) =780908a(8) =8000882a(9) =89763320a(10) =1094915222a(11) =14431179908a(12) =204423631178