G.f. A(x) satisfies: A(x) = Sum_{n>=0} (1 + x*(1+x)^n)^n * x^n / A(x)^n.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =4a(6) =8a(7) =22a(8) =63a(9) =190a(10) =618a(11) =2119a(12) =7617a(13) =28571a(14) =111271a(15) =448704a(16) =1869072a(17) =8024648a(18) =35445048a(19) =160820201a(20) =748525951a(21) =3569856592a(22) =17426990777a(23) =86999613910a(24) =443782312584