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 A185756 #4 Mar 30 2012 18:37:26
%S A185756 2,15,154,1995,31191,571221,11992688,283976517,7487521975,
%T A185756 217567092743,6907888374828,237951469523807,8838510559556783,
%U A185756 352160268261051113,14982705940607112640,677935029521206050505,32508195354031791206799
%N A185756 Column 1 of triangle A185755.
%C A185756 Column 0 of triangle A185755 equals n^(n-1).
%C A185756 A185755(n,k) equals the coefficient of x^n*y^k in the n-th iteration of x*(1+xy)/(1-x).
%o A185756 (PARI) {a(n)=local(A=x, G=x*(1+x*y)/(1-x)); for(i=1, n+1, A=subst(G, x, A+O(x^(n+2))));polcoeff(polcoeff(A, n+1,x),1,y)}
%Y A185756 Cf. A185755, A185757, A185758, A185759.
%K A185756 nonn
%O A185756 1,1
%A A185756 _Paul D. Hanna_, Feb 03 2011