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 A349886 #20 Dec 06 2021 03:09:55
%S A349886 1,2,18,19749,4295498995,298024323402930834,
%T A349886 10314425729813391637014599924,
%U A349886 256923578002288684397369021397408936103993,6277101735598268377660667072561845282166297358613176925573
%N A349886 a(n) = Sum_{k=0..n} k^(k*n).
%H A349886 Seiichi Manyama, <a href="/A349886/b349886.txt">Table of n, a(n) for n = 0..26</a>
%F A349886 G.f.: Sum_{k>=0} k^(k^2) * x^k/(1 - k^k * x).
%F A349886 a(n) ~ n^(n^2). - _Vaclav Kotesovec_, Dec 04 2021
%t A349886 Table[1 + Sum[k^(k*n), {k, 1, n}], {n, 0, 10}] (* _Vaclav Kotesovec_, Dec 04 2021 *)
%t A349886 a[n_] := Sum[If[k == 0, 1, k^(k*n)], {k, 0, n}]; Array[a, 9, 0] (* _Amiram Eldar_, Dec 04 2021 *)
%o A349886 (PARI) a(n) = sum(k=0, n, k^(k*n));
%o A349886 (PARI) my(N=10, x='x+O('x^N)); Vec(sum(k=0, N, k^k^2*x^k/(1-k^k*x)))
%Y A349886 Cf. A031971, A062970, A249459.
%K A349886 nonn
%O A349886 0,2
%A A349886 _Seiichi Manyama_, Dec 03 2021