G.f. A(x) satisfies A(x) = 1 + x/(1+x^2)^2 * A(x)^3.

Terms

a(0) =1a(1) =1a(2) =3a(3) =10a(4) =43a(5) =204a(6) =1018a(7) =5270a(8) =28047a(9) =152495a(10) =843396a(11) =4729896a(12) =26834766a(13) =153740975a(14) =888209382a(15) =5168763962a(16) =30269667603a(17) =178259462436