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 A180606 #2 Mar 30 2012 18:37:22
%S A180606 1,1,2,18,862,185582,165592644,599576207236,8764375895813558,
%T A180606 516573425446007525398,122710727732550268600238492,
%U A180606 117431929105754130321446873061820
%N A180606 G.f.: A(x) = exp( Sum_{n>=1} (2^n-1)^(n-1)*x^n/n ).
%e A180606 G.f.: A(x) = 1 + x + 2*x^2 + 18*x^3 + 862*x^4 + 185582*x^5 +...
%e A180606 log(A(x)) = x + 3*x^2/2 + 7^2*x^3/3 + 15^3*x^4/4 + 31^4*x^5/5 +...
%o A180606 (PARI) {a(n)=polcoeff(exp(sum(m=1,n,(2^m-1)^(m-1)*x^m/m)+x*O(x^n)),n)}
%Y A180606 Cf. A180602.
%K A180606 nonn
%O A180606 0,3
%A A180606 _Paul D. Hanna_, Sep 26 2010