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 A364590 #11 Jul 29 2023 10:48:24
%S A364590 1,1,1,1,2,4,7,11,19,37,74,142,268,518,1033,2077,4152,8290,16687,
%T A364590 33899,69148,141160,288650,592354,1220086,2519226,5210164,10794088,
%U A364590 22408556,46613554,97125751,202662419,423459427,886048249,1856448852,3894362560,8178530890
%N A364590 G.f. satisfies A(x) = 1/(1-x) + x^4*A(x)^3.
%F A364590 a(n) = Sum_{k=0..floor(n/4)} binomial(n-2*k,2*k) * binomial(3*k,k) / (2*k+1).
%o A364590 (PARI) a(n) = sum(k=0, n\4, binomial(n-2*k, 2*k)*binomial(3*k, k)/(2*k+1));
%Y A364590 Cf. A346073, A364591.
%Y A364590 Cf. A049130, A199475, A364589.
%K A364590 nonn,easy
%O A364590 0,5
%A A364590 _Seiichi Manyama_, Jul 29 2023