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 A191809 #7 Apr 19 2025 19:35:29
%S A191809 1,1,2,7,32,174,1071,7281,53943,432555,3743146,34934853,351853883,
%T A191809 3827477399,44985837602,570985992828,7814212692498,115024461077654,
%U A191809 1815588345261996,30628743324667923,550414603283527315,10503650627005928698
%N A191809 G.f. satisfies: A(x) = Sum_{n>=0} x^n*A(x)^binomial(n+2,3).
%e A191809 G.f.: A(x) = 1 + x + 2*x^2 + 7*x^3 + 32*x^4 + 174*x^5 + 1071*x^6 +...
%e A191809 where the g.f. satisfies:
%e A191809 A(x) = 1 + x*A(x) + x^2*A(x)^4 + x^3*A(x)^10 + x^4*A(x)^20 + x^5*A(x)^35 + x^6*A(x)^56 + x^7*A(x)^84 +...+ x^n*A(x)^(n*(n+1)*(n+2)/3!) +...
%o A191809 (PARI) {a(n)=local(A=1+x);for(i=1,n,A=1+sum(m=1,n,x^m*(A+x*O(x^n))^(m*(m+1)*(m+2)/3!)));polcoeff(A,n)}
%Y A191809 Cf. A107591, A191810, A191811, A191812.
%K A191809 nonn
%O A191809 0,3
%A A191809 _Paul D. Hanna_, Jun 16 2011