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 A366177 #9 Oct 03 2023 08:59:53
%S A366177 1,2,9,55,382,2866,22648,185722,1565725,13486036,118163960,1049908872,
%T A366177 9437623630,85671158757,784247925911,7231502249005,67106161264660,
%U A366177 626221543735984,5872908642398977,55323451127462123,523240983692525619,4966658879361416551
%N A366177 G.f. A(x) satisfies A(x) = 1/(1 - x) + x*A(x)^3/(1 - x)^2.
%F A366177 a(n) = Sum_{k=0..n} binomial(n+3*k,n-k) * binomial(3*k,k)/(2*k+1).
%o A366177 (PARI) a(n) = sum(k=0, n, binomial(n+3*k, n-k)*binomial(3*k, k)/(2*k+1));
%Y A366177 Partial sums give A364620.
%Y A366177 Cf. A199475, A346626, A366178.
%K A366177 nonn
%O A366177 0,2
%A A366177 _Seiichi Manyama_, Oct 03 2023