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

Terms

a(0) =1a(1) =1a(2) =1a(3) =0a(4) =-2a(5) =0a(6) =13a(7) =0a(8) =-145a(9) =0a(10) =2328a(11) =0a(12) =-49784a(13) =0a(14) =1358965a(15) =0a(16) =-46076544a(17) =0a(18) =1902202515a(19) =0a(20) =-94104681660a(21) =0a(23) =0a(25) =0a(27) =0a(29) =0a(31) =0a(33) =0