G.f. satisfies A(x) = 1 + x*A(x)^3/(1 - x^2*A(x)^6).

Terms

a(0) =1a(1) =1a(2) =3a(3) =13a(4) =67a(5) =379a(6) =2271a(7) =14158a(8) =90875a(9) =596506a(10) =3985661a(11) =27018149a(12) =185356123a(13) =1284502886a(14) =8978432666a(15) =63225825415a(16) =448131632123