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 A342394 #18 Mar 10 2021 12:28:44
%S A342394 1,3,11,68,629,7793,117655,2097228,43046772,1000000649,25937424611,
%T A342394 743008379146,23298085122493,793714773371841,29192926025401528,
%U A342394 1152921504608945960,48661191875666868497,2185911559738739835591,104127350297911241532859
%N A342394 a(n) = Sum_{k=1..n} k^(gcd(k,n) - 1).
%F A342394 If p is prime, a(p) = p-1 + p^(p-1) = A173235(p) = A056665(p).
%t A342394 a[n_] := Sum[k^(GCD[k, n] - 1), {k, 1, n}]; Array[a, 19] (* _Amiram Eldar_, Mar 10 2021 *)
%o A342394 (PARI) a(n) = sum(k=1, n, k^(gcd(k, n)-1));
%Y A342394 Cf. A056665, A173235, A342389, A342396.
%K A342394 nonn,easy
%O A342394 1,2
%A A342394 _Seiichi Manyama_, Mar 10 2021