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

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =13a(5) =72a(6) =465a(7) =3362a(8) =26531a(9) =224856a(10) =2024188a(11) =19202830a(12) =190857879a(13) =1978567663a(14) =21319434418a(15) =238109360460