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 A185758 #10 Feb 01 2025 14:54:37
%S A185758 2,15,120,1190,14595,215950,3761310,75550188,1721103648,43872089118,
%T A185758 1237592664451,38282002057156,1288537309627464,46886217384094764,
%U A185758 1834003542264708444,76744318019878844916,3420833746251201921980
%N A185758 A diagonal of triangle A185755.
%C A185758 A185755(n,k) equals the coefficient of x^n*y^k in the n-th iteration of x*(1+xy)/(1-x).
%o A185758 (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),n-1,y)}
%Y A185758 Cf. A185755, A185756, A185757, A185759.
%K A185758 nonn
%O A185758 1,1
%A A185758 _Paul D. Hanna_, Feb 03 2011