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 A124531 #5 Jun 14 2017 00:11:43
%S A124531 1,1,2,5,16,62,274,1332,6978,38873,228090,1399625,8933506,59066261,
%T A124531 403241292,2835267821,20490128048,151951503074,1154770194362,
%U A124531 8983396031267,71473650532630,581142591346325,4825842125683150
%N A124531 Row 1 of rectangular table A124530.
%C A124531 In table A124530, the g.f. of row n, R_n(y), simultaneously satisfies: R_n(y) = Sum_{k>=0} y^k*R_k(y)^(n*k) for n>=0.
%F A124531 G.f.: A(x) = Sum_{n>=0} x^n*R_n(x)^n, where R_n(x) is the g.f. of row n in table A124530.
%o A124531 (PARI) a(n)=local(R);R=vector(n+2,r,vector(n+2,c,if(r==1 || c<=2,1,r^(c-2)))); for(i=0,n,for(r=0,n,R[r+1]=Vec(sum(c=0,n,x^c*Ser(R[c+1])^(r*c)+O(x^(n+1)))))); R[2][n+1]
%Y A124531 Cf. A124530 (table); other rows: A124532, A124533, A124534, A124535, A124536.
%K A124531 nonn
%O A124531 0,3
%A A124531 _Paul D. Hanna_, Nov 05 2006