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 A342471 #20 May 08 2021 07:46:44
%S A342471 1,2,9,18,1025,130,279937,65794,10078209,2097154,100000000001,
%T A342471 16789506,106993205379073,156728328194,35185445863425,281479271743490,
%U A342471 295147905179352825857,203119913861122,708235345355337676357633,1152923703631151106
%N A342471 a(n) = Sum_{d|n} phi(d)^n.
%F A342471 a(n) = Sum_{k=1..n} phi(n/gcd(k, n))^(n-1).
%F A342471 G.f.: Sum_{k>=1} (phi(k)*x)^k/(1 - (phi(k)*x)^k).
%F A342471 If p is prime, a(p) = 1 + (p-1)^p = A110567(p-1).
%F A342471 a(n) = Sum_{k=1..n} phi(gcd(n,k))^n/phi(n/gcd(n,k)). - _Richard L. Ollerton_, May 07 2021
%t A342471 a[n_] := DivisorSum[n, EulerPhi[#]^n &]; Array[a, 20] (* _Amiram Eldar_, Mar 13 2021 *)
%o A342471 (PARI) a(n) = sumdiv(n, d, eulerphi(d)^n);
%o A342471 (PARI) a(n) = sum(k=1, n, eulerphi(n/gcd(k, n))^(n-1));
%o A342471 (PARI) my(N=40, x='x+O('x^N)); Vec(sum(k=1, N, (eulerphi(k)*x)^k/(1-(eulerphi(k)*x)^k)))
%Y A342471 Cf. A000010, A029939, A110567, A309369, A338997, A342470.
%K A342471 nonn
%O A342471 1,2
%A A342471 _Seiichi Manyama_, Mar 13 2021