G.f. satisfies A(x) = 1 + x*(1 + x*A(x)^2)^4.

Terms

a(0) =1a(1) =1a(2) =4a(3) =14a(4) =64a(5) =301a(6) =1500a(7) =7738a(8) =40948a(9) =221278a(10) =1215284a(11) =6765148a(12) =38083556a(13) =216431253a(14) =1240048740a(15) =7155236960a(16) =41542685352a(17) =242513393884