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

Terms

a(0) =1a(1) =1a(2) =3a(3) =10a(4) =41a(5) =186a(6) =922a(7) =4911a(8) =27830a(9) =166656a(10) =1049410a(11) =6922476a(12) =47698148a(13) =342483885a(14) =2557538781a(15) =19829608532a(16) =159393394129