Reversion of x-x^2-x^3-2*x^4.

Terms

a(0) =1a(1) =1a(2) =3a(3) =12a(4) =50a(5) =224a(6) =1054a(7) =5121a(8) =25509a(9) =129591a(10) =668811a(11) =3496740a(12) =18481512a(13) =98585788a(14) =530068840a(15) =2869725800a(16) =15630429306a(17) =85589391884a(18) =470905310206