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 A383538 #9 Apr 29 2025 08:54:26
%S A383538 1,1,1,1,26,73,148,257,2431,9676,26984,61993,332762,1487886,5029676,
%T A383538 13986049,57394823,253491517,953613991,3032424076,11249004334,
%U A383538 47032861778,185321607072,645015386921,2340940921276,9321743657318,37091865274327,136525692171310
%N A383538 a(n) = Sum_{k=0..floor(n/4)} binomial(n+k,k)^2 * binomial(n-3*k,k).
%C A383538 Diagonal of the rational function 1 / ((1-x)*(1-y)*(1-z) - z^4).
%o A383538 (PARI) a(n) = sum(k=0, n\4, binomial(n+k, k)^2*binomial(n-3*k, k));
%Y A383538 Cf. A383536, A383537.
%K A383538 nonn
%O A383538 0,5
%A A383538 _Seiichi Manyama_, Apr 29 2025