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 A342412 #13 Mar 11 2021 17:32:15
%S A342412 1,2,7,37,501,2771,100843,1056833,28702189,401562757,23579476911,
%T A342412 247792605523,21505924728445,340246521979079,15569565432876147,
%U A342412 576478345026355201,45798768824157052689,728648310343004595593,98646963440126439346903
%N A342412 a(n) = Sum_{k=1..n} (n/gcd(k,n))^(n-2).
%F A342412 a(n) = Sum_{d|n} phi(d^(n-1)) = Sum_{d|n} phi(d) * d^(n-2).
%F A342412 G.f.: Sum_{k>=1} phi(k^(k-1))*x^k/(1 - (k*x)^k).
%t A342412 a[n_] := Sum[(n/GCD[k, n])^(n - 2), {k, 1, n}]; Array[a, 20] (* _Amiram Eldar_, Mar 11 2021 *)
%o A342412 (PARI) a(n) = sum(k=1, n, (n/gcd(k, n))^(n-2));
%o A342412 (PARI) a(n) = sumdiv(n, d, eulerphi(d^(n-1)));
%o A342412 (PARI) a(n) = sumdiv(n, d, eulerphi(d)*d^(n-2));
%o A342412 (PARI) my(N=20, x='x+O('x^N)); Vec(sum(k=1, N, eulerphi(k^(k-1))*x^k/(1-(k*x)^k)))
%Y A342412 Cf. A000010, A226561, A321349, A342411.
%K A342412 nonn
%O A342412 1,2
%A A342412 _Seiichi Manyama_, Mar 11 2021