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 A342473 #19 May 09 2021 08:06:46
%S A342473 1,2,9,18,1025,74,279937,65554,10077705,1049602,100000000001,16777306,
%T A342473 106993205379073,78364444034,35184372089865,281474976776210,
%U A342473 295147905179352825857,101559966746186,708235345355337676357633,1152921504607896594,46005119909369701746057,10000000000100000000002
%N A342473 a(n) = Sum_{d|n} phi(d)^d.
%H A342473 Seiichi Manyama, <a href="/A342473/b342473.txt">Table of n, a(n) for n = 1..388</a>
%F A342473 a(n) = Sum_{k=1..n} phi(n/gcd(k, n))^(n/gcd(k, n) - 1).
%F A342473 G.f.: Sum_{k>=1} (phi(k) * x)^k/(1 - x^k).
%F A342473 If p is prime, a(p) = 1 + (p-1)^p = A110567(p-1).
%F A342473 a(n) = Sum_{k=1..n} phi(gcd(n,k))^gcd(n,k)/phi(n/gcd(n,k)). - _Richard L. Ollerton_, May 07 2021
%t A342473 a[n_] := DivisorSum[n, EulerPhi[#]^# &]; Array[a, 20] (* _Amiram Eldar_, Mar 14 2021 *)
%o A342473 (PARI) a(n) = sumdiv(n, d, eulerphi(d)^d);
%o A342473 (PARI) a(n) = sum(k=1, n, eulerphi(n/gcd(k, n))^(n/gcd(k, n)-1));
%o A342473 (PARI) my(N=40, x='x+O('x^N)); Vec(sum(k=1, N, (eulerphi(k)*x)^k/(1-x^k)))
%Y A342473 Cf. A000010, A029939, A110567, A309369, A338997, A342470, A342471, A342485.
%K A342473 nonn
%O A342473 1,2
%A A342473 _Seiichi Manyama_, Mar 13 2021