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

Terms

a(0) =1a(1) =1a(2) =2a(3) =5a(4) =12a(5) =32a(6) =84a(7) =234a(8) =652a(9) =1872a(10) =5416a(11) =15922a(12) =47188a(13) =141283a(14) =425910a(15) =1293105a(16) =3948080a(17) =12118619a(18) =37367694a(19) =115708111a(20) =359623780a(21) =1121543440a(22) =3508533500a(23) =11006973980a(24) =34620982004a(25) =109157354769a(26) =344928572562