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

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =3a(6) =7a(7) =11a(8) =28a(9) =46a(10) =123a(11) =207a(12) =572a(13) =979a(14) =2769a(15) =4797a(16) =13806a(17) =24138a(18) =70414a(19) =123998a(20) =365636a(21) =647615a(22) =1926505a(23) =3428493a(24) =10273870a(25) =18356714a(26) =55349155a(27) =99229015a(28) =300783420a(29) =540807165