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 A352983 #20 Apr 16 2022 09:34:11
%S A352983 1,0,1,1,257,1025,535538,4799354,4338079554,69107159370,
%T A352983 96470431101379,2401809362313955,4798267740520031875,
%U A352983 172076350440523281571,466164803742660494432996,22761346686115003736962100,80340572151131167125889902852
%N A352983 a(n) = Sum_{k=0..floor(n/2)} k^(2*n).
%H A352983 Seiichi Manyama, <a href="/A352983/b352983.txt">Table of n, a(n) for n = 0..240</a>
%F A352983 G.f.: Sum_{k>=0} (k^2 * x)^(2 * k) / (1 - k^2 * x).
%F A352983 a(n) ~ exp(3 + (-1)^n) * (n/2)^(2*n) / (exp(4) - 1). - _Vaclav Kotesovec_, Apr 14 2022
%t A352983 a[0] = 1; a[n_] := Sum[k^(2*n), {k, 0, Floor[n/2]}]; Array[a, 17, 0] (* _Amiram Eldar_, Apr 13 2022 *)
%o A352983 (PARI) a(n) = sum(k=0, n\2, k^(2*n));
%o A352983 (PARI) my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, (k^2*x)^(2*k)/(1-k^2*x)))
%Y A352983 Cf. A249459, A352984.
%K A352983 nonn,easy
%O A352983 0,5
%A A352983 _Seiichi Manyama_, Apr 13 2022