G.f. satisfies A(x) = 1 + x*(1 + x*A(x)^2)^5.

Terms

a(0) =1a(1) =1a(2) =5a(3) =20a(4) =105a(5) =575a(6) =3306a(7) =19760a(8) =121035a(9) =757230a(10) =4815530a(11) =31039402a(12) =202335855a(13) =1331569725a(14) =8834918160a(15) =59035907480a(16) =396937508816