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 A356506 #5 Aug 10 2022 07:56:52
%S A356506 1,6,120,3250,103020,3587696,133101836,5167564380,207615129579,
%T A356506 8567305854998,361201849117032,15498967122249676,674906101555736960,
%U A356506 29757755664623031984,1326196334421645347368,59655785739373960058296,2705420198806474232850741
%N A356506 a(n) = A356500(3*n, n+1) for n >= 0.
%C A356506 Triangle A356500 describes the coefficients in G(x,y) that satisfies: y = Sum_{n=-oo..+oo} (-x)^(n^2) * G(x,y)^((n-1)^2).
%o A356506 (PARI) {A356500(n,k) = my(A=[y],M); for(i=1,n, A = concat(A,0); M = ceil(sqrt(n+1));
%o A356506 A[#A] = -polcoeff( sum(m=-M,M, (-x)^(m^2)*Ser(A)^((m-1)^2)), #A-1)); polcoeff(A[n+1],k,y) }
%o A356506 for(n=0,20, print1( A356500(3*n, n+1),", "))
%Y A356506 Cf. A356500, A356504, A356505.
%K A356506 nonn
%O A356506 0,2
%A A356506 _Paul D. Hanna_, Aug 09 2022