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 A308593 #19 Jun 10 2019 08:34:04
%S A308593 1,5,28,513,3126,840242,823544,8606711809,7625984905477,
%T A308593 1221277338483250,285311670612,89215914432866222355906,
%U A308593 302875106592254,316913110043605007120962336162,608295209422788113565012727970423808,680564733921105089459460296530789924865
%N A308593 a(n) = Sum_{d|n} d^(n^2/d).
%H A308593 Seiichi Manyama, <a href="/A308593/b308593.txt">Table of n, a(n) for n = 1..80</a>
%t A308593 Table[Sum[d^(n^2/d), {d, Divisors[n]}], {n,1,20}] (* _Vaclav Kotesovec_, Jun 09 2019 *)
%o A308593 (PARI) {a(n) = sumdiv(n, d, d^(n^2/d))}
%Y A308593 Diagonal of A308509.
%Y A308593 Cf. A023887, A055225, A308571.
%K A308593 nonn
%O A308593 1,2
%A A308593 _Seiichi Manyama_, Jun 09 2019