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 A360728 #13 Feb 18 2023 19:00:19
%S A360728 1,1,4,27,257,3133,46737,824567,16792845,387700506,10005766337,
%T A360728 285445919589,8919587932524,302975123887680,11115145723728035,
%U A360728 438000897534309171,18450681900124075166,827395845674975999727,39352977072147424071861
%N A360728 Expansion of Sum_{k>=0} (k * x * (1 + x^3))^k.
%H A360728 Winston de Greef, <a href="/A360728/b360728.txt">Table of n, a(n) for n = 0..385</a>
%F A360728 a(n) = Sum_{k=0..floor(n/4)} (n-3*k)^(n-3*k) * binomial(n-3*k,k).
%o A360728 (PARI) my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, (k*x*(1+x^3))^k))
%o A360728 (PARI) a(n) = sum(k=0, n\4, (n-3*k)^(n-3*k)*binomial(n-3*k, k));
%Y A360728 Cf. A360611, A360727.
%Y A360728 Cf. A360731.
%K A360728 nonn
%O A360728 0,3
%A A360728 _Seiichi Manyama_, Feb 18 2023