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 A360776 #9 Feb 20 2023 07:50:28
%S A360776 1,1,4,27,257,3129,46683,823799,16780342,387467154,10000823639,
%T A360776 285328449077,8916487888186,302885106945216,11112292144568909,
%U A360776 437902806653498835,18447046953316227905,827251374022851280231,39346845973273509115167
%N A360776 Expansion of Sum_{k>=0} (x * (k + x^3))^k.
%F A360776 a(n) = Sum_{k=0..floor(n/4)} (n-3*k)^(n-4*k) * binomial(n-3*k,k).
%o A360776 (PARI) my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, (x*(k+x^3))^k))
%o A360776 (PARI) a(n) = sum(k=0, n\4, (n-3*k)^(n-4*k)*binomial(n-3*k, k));
%Y A360776 Cf. A360774, A360775.
%Y A360776 Cf. A360032, A360728.
%K A360776 nonn
%O A360776 0,3
%A A360776 _Seiichi Manyama_, Feb 20 2023