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 A364473 #8 Jul 26 2023 18:02:47
%S A364473 1,1,3,13,65,353,2024,12057,73890,462851,2950261,19073921,124776881,
%T A364473 824409052,5493384031,36874564529,249114808794,1692489908494,
%U A364473 11556616157589,79265016880139,545860966841247,3772800724433931,26162662010039826,181974370638420829
%N A364473 G.f. satisfies A(x) = 1 + x*A(x)^2 + x^2*A(x)^6.
%F A364473 a(n) = Sum_{k=0..floor(n/2)} binomial(2*n+2*k,k) * binomial(2*n+k,n-2*k) / (n+3*k+1).
%o A364473 (PARI) a(n) = sum(k=0, n\2, binomial(2*n+2*k, k)*binomial(2*n+k, n-2*k)/(n+3*k+1));
%Y A364473 Cf. A001002, A001764, A006605, A052709, A143330, A364477.
%Y A364473 Cf. A364472, A364474.
%K A364473 nonn
%O A364473 0,3
%A A364473 _Seiichi Manyama_, Jul 26 2023