G.f. A(x) satisfies: A(x) = x + x^2 * exp( Sum_{k>=1} (-1)^(k+1) * A(x^k)^2 / k ).

Terms

a(0) =1a(1) =1a(2) =0a(3) =1a(4) =2a(5) =1a(6) =4a(7) =8a(8) =10a(9) =22a(10) =50a(11) =77a(12) =160a(13) =343a(14) =622a(15) =1250a(16) =2648a(17) =5127a(18) =10364a(19) =21685a(20) =43594a(21) =88907a(22) =185458a(23) =380113a(24) =782902a(25) =1633841a(26) =3387444a(27) =7033401a(28) =14716304a(29) =30734066