This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A202518 #10 Mar 30 2012 18:37:33 %S A202518 1,1,4,111,12600,5722258,10419647136,76124127132667, %T A202518 2234758718926030048,263964471372716219981614, %U A202518 125532541357451846737479404864,240382906462440786858510574342553910,1852958218856132372722626702327036659515008 %N A202518 G.f. satisfies: A(x) = exp( Sum_{n>=1} (2^n - A(x))^n * x^n/n ). %C A202518 Compare g.f. with: G(x) = exp(Sum_{n>=1} (2 - G(x))^n * x^n/n) = 1 + x*C(-x^2) where C(x) is the Catalan function (A000108). %e A202518 G.f.: A(x) = 1 + x + 4*x^2 + 111*x^3 + 12600*x^4 + 5722258*x^5 +... %e A202518 where %e A202518 log(A(x)) = (2 - A(x))*x + (2^2 - A(x))^2*x^2/2 + (2^3 - A(x))^3*x^3/3 + (2^4 - A(x))^4*x^4/4 +... %o A202518 (PARI) {a(n)=local(A=1+x);for(i=1,n,A=exp(sum(m=1,n,(2^m-A+x*O(x^n))^m*x^m/m)));polcoeff(A,n)} %Y A202518 Cf. A163138, A155200. %K A202518 nonn %O A202518 0,3 %A A202518 _Paul D. Hanna_, Dec 20 2011