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 A366216 #8 Oct 04 2023 12:51:01
%S A366216 1,1,8,60,520,4886,48384,497460,5259872,56834345,624819148,6966612604,
%T A366216 78592083420,895432704860,10288759392156,119089472755860,
%U A366216 1387274092156508,16251727492295812,191342076640423136,2262894045516407118,26869820052175649836
%N A366216 G.f. A(x) satisfies A(x) = 1 + x*(1 + x)^4*A(x)^4.
%F A366216 a(n) = Sum_{k=0..n} binomial(4*k,n-k) * binomial(4*k,k)/(3*k+1).
%o A366216 (PARI) a(n) = sum(k=0, n, binomial(4*k, n-k)*binomial(4*k, k)/(3*k+1));
%Y A366216 Cf. A073155, A366200.
%K A366216 nonn
%O A366216 0,3
%A A366216 _Seiichi Manyama_, Oct 04 2023