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

Terms

a(0) =1a(1) =2a(2) =-2a(3) =14a(4) =-70a(5) =426a(6) =-2714a(7) =18118a(8) =-124814a(9) =881042a(10) =-6339058a(11) =46318334a(12) =-342769750a(13) =2563781690a(14) =-19350683018a(15) =147197511222