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

Terms

a(0) =1a(1) =1a(2) =3a(3) =11a(4) =49a(5) =237a(6) =1211a(7) =6423a(8) =35025a(9) =195129a(10) =1105811a(11) =6354627a(12) =36942817a(13) =216879877a(14) =1283942091a(15) =7656313775a(16) =45945786849a(17) =277266497649