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

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =8a(5) =17a(6) =42a(7) =107a(8) =272a(9) =719a(10) =1914a(11) =5163a(12) =14088a(13) =38733a(14) =107370a(15) =299511a(16) =840372a(17) =2370020a(18) =6714316a(19) =19100096a(20) =54534696a(21) =156230943a(22) =448942998a(23) =1293692305a(24) =3737568960a(25) =10823759093a(26) =31413810702a(27) =91358248179a(28) =266193726712a(29) =776989772307