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

Terms

a(0) =1a(1) =2a(2) =5a(3) =14a(4) =47a(5) =194a(6) =977a(7) =5870a(8) =41099a(9) =328802a(10) =2959229a(11) =29592302a(12) =325515335a(13) =3906184034a(14) =50780392457a(15) =710925494414