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 A366434 #11 Oct 10 2023 05:09:24
%S A366434 1,1,-4,16,-84,496,-3140,20832,-142932,1005856,-7220100,52657392,
%T A366434 -389088084,2906551440,-21914464708,166548194240,-1274531623764,
%U A366434 9812792232768,-75955668337412,590742300208848,-4614140648464980,36178872976542768,-284664427193774916
%N A366434 G.f. A(x) satisfies A(x) = 1 + x * ((1 - x) / A(x))^2.
%F A366434 a(n) = (-1)^(n-1) * Sum_{k=0..n} binomial(3*k-1,k) * binomial(2*k,n-k) / (3*k-1).
%o A366434 (PARI) a(n) = (-1)^(n-1)*sum(k=0, n, binomial(3*k-1, k)*binomial(2*k, n-k)/(3*k-1));
%Y A366434 Partial sums give A366364.
%Y A366434 Cf. A366431, A366432, A366433, A366435, A366436, A366437.
%K A366434 sign
%O A366434 0,3
%A A366434 _Seiichi Manyama_, Oct 09 2023