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

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =22a(5) =89a(6) =381a(7) =1694a(8) =7744a(9) =36168a(10) =171831a(11) =827814a(12) =4034589a(13) =19857262a(14) =98555324a(15) =492710856a(16) =2478897620a(17) =12541604830a(18) =63768192378a(19) =325674039636