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

Terms

a(0) =1a(1) =0a(2) =1a(3) =4a(4) =14a(5) =66a(6) =397a(7) =2626a(8) =18797a(9) =148238a(10) =1281134a(11) =11943790a(12) =118998365a(13) =1262189748a(14) =14203022537a(15) =168835162632