E.g.f.: exp(x)-1+log(-1/(-2+exp(x))).

Terms

a(0) =0a(1) =2a(2) =3a(3) =7a(4) =27a(5) =151a(6) =1083a(7) =9367a(8) =94587a(9) =1091671a(10) =14174523a(11) =204495127a(12) =3245265147a(13) =56183135191