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 A352984 #20 Apr 16 2022 09:34:05
%S A352984 1,0,0,1,1,1,262145,2097153,16777217,7625731702716,205892205836474,
%T A352984 5559069156490116,4722516577573661689554,302235507459360068466700,
%U A352984 19342922532827596354169130,28422947373397605556855075614825,3552792907042781637051562368414979
%N A352984 a(n) = Sum_{k=0..floor(n/3)} k^(3*n).
%H A352984 Seiichi Manyama, <a href="/A352984/b352984.txt">Table of n, a(n) for n = 0..185</a>
%F A352984 G.f.: Sum_{k>=0} (k^3 * x)^(3 * k) / (1 - k^3 * x).
%t A352984 a[0] = 1; a[n_] := Sum[k^(3*n), {k, 0, Floor[n/3]}]; Array[a, 16, 0] (* _Amiram Eldar_, Apr 13 2022 *)
%o A352984 (PARI) a(n) = sum(k=0, n\3, k^(3*n));
%o A352984 (PARI) my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, (k^3*x)^(3*k)/(1-k^3*x)))
%Y A352984 Cf. A352983.
%K A352984 nonn,easy
%O A352984 0,7
%A A352984 _Seiichi Manyama_, Apr 13 2022