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 A364477 #9 Jul 26 2023 18:02:42
%S A364477 1,1,3,14,76,448,2791,18078,120516,821435,5698422,40101623,285583775,
%T A364477 2054272430,14903954415,108932920861,801350333186,5928653489398,
%U A364477 44084056075057,329279673851792,2469493161891742,18588339309502760,140383789476473354
%N A364477 G.f. satisfies A(x) = 1 + x*A(x)^2 + x^2*A(x)^7.
%F A364477 a(n) = Sum_{k=0..floor(n/2)} binomial(2*n+3*k,k) * binomial(2*n+2*k,n-2*k) / (n+4*k+1).
%o A364477 (PARI) a(n) = sum(k=0, n\2, binomial(2*n+3*k, k)*binomial(2*n+2*k, n-2*k)/(n+4*k+1));
%Y A364477 Cf. A001002, A001764, A006605, A052709, A143330, A364473.
%Y A364477 Cf. A364476.
%K A364477 nonn
%O A364477 0,3
%A A364477 _Seiichi Manyama_, Jul 26 2023