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 A342620 #18 Mar 18 2021 08:25:29
%S A342620 1,2,33,66,16385,770,10077697,1050626,362805249,83886082,
%T A342620 10000000000001,268664834,15407021574586369,19747769352194,
%U A342620 2252074693689345,18014673389486082,75557863725914323419137,25593109118189570,229468251895129407139872769,73788172563556335618,6624765697237267477692417,11000000000000000000000002
%N A342620 a(n) = Sum_{d|n} phi(n/d)^(n+d+1).
%H A342620 Seiichi Manyama, <a href="/A342620/b342620.txt">Table of n, a(n) for n = 1..388</a>
%F A342620 a(n) = Sum_{k=1..n} phi(n/gcd(k,n))^(n + gcd(k,n)).
%F A342620 G.f.: Sum_{k>=1} phi(k)^(k+2) * x^k/(1 - phi(k)^(k+1) * x^k).
%F A342620 If p is prime, a(p) = 1 + (p-1)^(p+2).
%t A342620 a[n_] := DivisorSum[n, EulerPhi[n/#]^(n + # + 1) &]; Array[a, 20] (* _Amiram Eldar_, Mar 17 2021 *)
%o A342620 (PARI) a(n) = sumdiv(n, d, eulerphi(n/d)^(n+d+1));
%o A342620 (PARI) a(n) = sum(k=1, n, eulerphi(n/gcd(k, n))^(n+gcd(k, n)));
%o A342620 (PARI) my(N=40, x='x+O('x^N)); Vec(sum(k=1, N, eulerphi(k)^(k+2)*x^k/(1-eulerphi(k)^(k+1)*x^k)))
%Y A342620 Cf. A000010, A342613.
%K A342620 nonn
%O A342620 1,2
%A A342620 _Seiichi Manyama_, Mar 16 2021