Expansion of exp(x/(1-x-2x^2)).

Terms

a(0) =1a(1) =1a(2) =3a(3) =25a(4) =217a(5) =2541a(6) =34531a(7) =550453a(8) =9957585a(9) =202137337a(10) =4543312771a(11) =112004037201