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 A366357 #10 Oct 08 2023 10:50:37
%S A366357 1,2,-3,19,-105,690,-4781,34708,-260189,1999169,-15660175,124596499,
%T A366357 -1004110947,8179379808,-67239070867,557098881920,-4647368670949,
%U A366357 39001655222788,-329048378867467,2789241880512899,-23743798316713367,202894843070927860
%N A366357 G.f. satisfies A(x) = 1/(1 - x) + x/A(x)^2.
%F A366357 a(n) = (-1)^(n-1) * Sum_{k=0..n} binomial(3*k-1,k) * binomial(3*k-1,n-k)/(3*k-1).
%o A366357 (PARI) a(n) = (-1)^(n-1)*sum(k=0, n, binomial(3*k-1, k)*binomial(3*k-1, n-k)/(3*k-1));
%Y A366357 Cf. A007317, A199475, A349289, A349290, A349291, A349292, A349293, A366356, A366358, A366359.
%Y A366357 Cf. A364393, A366326, A366364.
%K A366357 sign
%O A366357 0,2
%A A366357 _Seiichi Manyama_, Oct 08 2023