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 A364552 #9 Jul 28 2023 10:36:26
%S A364552 1,1,1,1,2,5,11,21,39,78,169,373,808,1727,3719,8153,18100,40315,89770,
%T A364552 200250,448755,1010685,2284295,5173961,11740697,26699780,60863291,
%U A364552 139045991,318247190,729572315,1675085099,3851795549,8869990949,20453679944,47223844863
%N A364552 G.f. satisfies A(x) = 1 + x*A(x) + x^4*A(x)^3.
%F A364552 a(n) = Sum_{k=0..floor(n/4)} binomial(n-k,3*k) * binomial(3*k,k) / (2*k+1).
%o A364552 (PARI) a(n) = sum(k=0, n\4, binomial(n-k, 3*k)*binomial(3*k, k)/(2*k+1));
%Y A364552 Cf. A000108, A071879, A346626.
%Y A364552 Cf. A023426, A063019, A127902.
%K A364552 nonn,easy
%O A364552 0,5
%A A364552 _Seiichi Manyama_, Jul 28 2023