G.f. A(x) satisfies: A(x) = ((1 + x)/(1 - x)) * A(x^2)^2*A(x^3)^3*A(x^4)^4* ... *A(x^k)^k* ...

Terms

a(0) =1a(1) =2a(2) =6a(3) =16a(4) =46a(5) =104a(6) =268a(7) =596a(8) =1406a(9) =3060a(10) =6812a(11) =14356a(12) =30948a(13) =63660a(14) =132328a(15) =267164a(16) =541678a(17) =1072000a(18) =2127052a(19) =4140340a(20) =8060588a(21) =15458948a(22) =29602504a(23) =55990780a(24) =105693252a(25) =197422424a(26) =367793952a(27) =679206200a(28) =1250557768a(29) =2284986580