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 A366499 #10 Oct 11 2023 08:42:37
%S A366499 1,1,-5,25,-145,945,-6641,49057,-375361,2948353,-23634049,192554753,
%T A366499 -1589812225,13272519937,-111850866433,950220134913,-8129133081601,
%U A366499 69971682467841,-605546841831425,5265763716550657,-45988028107350017,403192288488677377
%N A366499 G.f. A(x) satisfies A(x) = 1 + x / ((1+x)^3*A(x)^2).
%F A366499 G.f.: A(x) = 1/B(-x) where B(x) is the g.f. of A213282.
%F A366499 a(n) = (-1)^(n-1) * Sum_{k=0..n} binomial(n+2*k-1,n-k) * binomial(3*k-1,k) / (3*k-1).
%o A366499 (PARI) a(n) = (-1)^(n-1)*sum(k=0, n, binomial(n+2*k-1, n-k)*binomial(3*k-1, k)/(3*k-1));
%Y A366499 Cf. A001006, A366221, A366272, A366273, A366495, A366496, A366497, A366498, A366500, A366501.
%Y A366499 Cf. A213282.
%K A366499 sign
%O A366499 0,3
%A A366499 _Seiichi Manyama_, Oct 11 2023