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 A352981 #24 Nov 02 2022 10:29:51
%S A352981 1,0,1,1,17,33,794,2316,72354,282340,10874275,53201625,2438235715,
%T A352981 14350108521,762963987380,5249352196144,317685943157892,
%U A352981 2502137235710736,169842891165484965,1506994510201252425,113394131858832552133,1119223325228757961465
%N A352981 a(n) = Sum_{k=0..floor(n/2)} k^n.
%H A352981 Seiichi Manyama, <a href="/A352981/b352981.txt">Table of n, a(n) for n = 0..429</a>
%F A352981 G.f.: Sum_{k>=0} (k * x)^(2 * k) / (1 - k * x).
%F A352981 a(n) ~ exp((3 + (-1)^n)/2) * (n/2)^n / (exp(2) - 1). - _Vaclav Kotesovec_, Apr 14 2022
%t A352981 a[0] = 1; a[n_] := Sum[k^n, {k, 0, Floor[n/2]}]; Array[a, 22, 0] (* _Amiram Eldar_, Apr 13 2022 *)
%o A352981 (PARI) a(n) = sum(k=0, n\2, k^n);
%o A352981 (PARI) my(N=40, x='x+O('x^N)); Vec(sum(k=0, N, (k*x)^(2*k)/(1-k*x)))
%o A352981 (Magma) [(&+[k^n: k in [0..Floor(n/2)]]): n in [0..40]]; // _G. C. Greubel_, Nov 01 2022
%o A352981 (SageMath) [sum( k^n for k in range((n//2)+1)) for n in range(41)] # _G. C. Greubel_, Nov 01 2022
%Y A352981 Cf. A089072, A104872, A352982, A352983.
%K A352981 nonn,easy
%O A352981 0,5
%A A352981 _Seiichi Manyama_, Apr 13 2022