G.f. satisfies A(x) = 1 - x^3 + x*A(x)^4.

Terms

a(0) =1a(1) =1a(2) =4a(3) =21a(4) =136a(5) =941a(6) =6864a(7) =52006a(8) =405312a(9) =3228654a(10) =26170764a(11) =215166638a(12) =1789998808a(13) =15040070843a(14) =127450104568