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 A363380 #6 May 29 2023 22:38:31
%S A363380 1,2,20,284,4712,85392,1638112,32699472,672188768,14133399744,
%T A363380 302535052160,6570819330688,144442463464704,3207564324825600,
%U A363380 71848240540852224,1621452789508328704,36831997860270007808,841470878382566444032
%N A363380 G.f. satisfies A(x) = 1 + x * A(x)^4 * (1 + A(x)^2).
%F A363380 a(n) = Sum_{k=0..n} binomial(n,k) * binomial(4*n+2*k+1,n)/(4*n+2*k+1).
%o A363380 (PARI) a(n) = sum(k=0, n, binomial(n, k)*binomial(4*n+2*k+1, n)/(4*n+2*k+1));
%Y A363380 Cf. A219534, A346626, A363311.
%Y A363380 Cf. A217360, A260332, A363304.
%K A363380 nonn,easy
%O A363380 0,2
%A A363380 _Seiichi Manyama_, May 29 2023