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 A366593 #10 Oct 14 2023 13:20:02
%S A366593 1,0,1,3,7,25,82,278,992,3552,12985,48107,179977,680079,2589915,
%T A366593 9931573,38319117,148640195,579349123,2267818509,8911575579,
%U A366593 35141656433,139018921717,551557089103,2194155973751,8750097458849,34973989188202,140085055366350
%N A366593 G.f. A(x) satisfies A(x) = 1 + x^2*(1+x)^3*A(x)^4.
%F A366593 a(n) = Sum_{k=0..floor(n/2)} binomial(3*k,n-2*k) * binomial(4*k,k)/(3*k+1).
%o A366593 (PARI) a(n) = sum(k=0, n\2, binomial(3*k, n-2*k)*binomial(4*k, k)/(3*k+1));
%Y A366593 Cf. A366272, A366594, A366595.
%Y A366593 Cf. A137954.
%K A366593 nonn
%O A366593 0,4
%A A366593 _Seiichi Manyama_, Oct 14 2023