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

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =12a(5) =62a(6) =385a(7) =2781a(8) =22848a(9) =210176a(10) =2139336a(11) =23872450a(12) =289825228a(13) =3803859030a(14) =53676793157a(15) =810508456373