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 A373004 #9 May 19 2024 09:41:40
%S A373004 1,8,81,1054,15625,279936,5764801,134480378,3486843447,100000000000,
%T A373004 3138428376721,107006262884442,3937376385699289,155568095557812224,
%U A373004 6568408355712890625,295150156996346511346,14063084452067724991009,708235345964697414795264
%N A373004 a(n) = Sum_{k=1..n} sigma( (n/gcd(k,n))^n ).
%F A373004 If k is squarefree (cf. A005117) then a(k) = k^(k+1).
%F A373004 a(n) = Sum_{d|n} phi(d) * sigma(d^n).
%o A373004 (PARI) a(n) = sumdiv(n, d, eulerphi(d)*sigma(d^n));
%Y A373004 Cf. A062952, A372227, A372998, A373000.
%Y A373004 Cf. A005117, A007778.
%K A373004 nonn
%O A373004 1,2
%A A373004 _Seiichi Manyama_, May 19 2024