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

Terms

a(0) =1a(1) =2a(2) =3a(3) =13a(4) =32a(5) =147a(6) =445a(7) =2067a(8) =7019a(9) =32590a(10) =119209a(11) =551551a(12) =2125429a(13) =9795863a(14) =39221165a(15) =180177403a(16) =742575760a(17) =3403131833a(18) =14342166121a(19) =65626369612a(20) =281459129188