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 A342489 #16 Mar 20 2021 11:02:31
%S A342489 1,2,5,10,257,38,46657,16394,1679621,262402,10000000001,4194350,
%T A342489 8916100448257,13060740674,4398046511365,35184372105226,
%U A342489 18446744073709551617,16926661124390,39346408075296537575425,144115188076118282,3833759992447475168837
%N A342489 a(n) = Sum_{d|n} phi(d)^(d-1).
%H A342489 Seiichi Manyama, <a href="/A342489/b342489.txt">Table of n, a(n) for n = 1..388</a>
%F A342489 a(n) = Sum_{k=1..n} phi(n/gcd(k, n))^(n/gcd(k, n) - 2).
%F A342489 G.f.: Sum_{k>=1} phi(k)^(k-1) * x^k/(1 - x^k).
%F A342489 If p is prime, a(p) = 1 + (p-1)^(p-1) = A014566(p-1).
%t A342489 a[n_] := DivisorSum[n, EulerPhi[#]^(#-1) &]; Array[a, 20] (* _Amiram Eldar_, Mar 14 2021 *)
%o A342489 (PARI) a(n) = sumdiv(n, d, eulerphi(d)^(d-1));
%o A342489 (PARI) a(n) = sum(k=1, n, eulerphi(n/gcd(k, n))^(n/gcd(k, n)-2));
%o A342489 (PARI) my(N=40, x='x+O('x^N)); Vec(sum(k=1, N, eulerphi(k)^(k-1)*x^k/(1-x^k)))
%Y A342489 Cf. A000010, A014566, A164941, A342473, A342485.
%K A342489 nonn
%O A342489 1,2
%A A342489 _Seiichi Manyama_, Mar 13 2021