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 A332653 #8 Sep 08 2022 08:46:25 %S A332653 1,2,5,19,157,1306,19609,266372,5321721,101001214,2593742461, %T A332653 61920391842,1941507093541,56984643437138,2076518238897649, %U A332653 72340172854919941,3041324492229179281,121440691499123469858,5784852794328402307381,262799364106291328009626 %N A332653 a(n) = (1/n) * Sum_{k=1..n} n^(k/gcd(n, k)). %F A332653 a(n) = (1/n) * Sum_{k=1..n} n^(lcm(n, k)/n). %F A332653 a(n) = Sum_{d|n} Sum_{k=1..d, gcd(k, d) = 1} n^(k-1). %F A332653 a(n) = A332652(n) / n. %t A332653 Table[(1/n) Sum[n^(k/GCD[n, k]), {k, 1, n}], {n, 1, 20}] %t A332653 Table[Sum[Sum[If[GCD[k, d] == 1, n^(k - 1), 0], {k, 1, d}], {d, Divisors[n]}], {n, 1, 20}] %o A332653 (Magma) [(1/n)*&+[n^(k div Gcd(n,k)):k in [1..n]]:n in [1..21]]; // _Marius A. Burtea_, Feb 18 2020 %Y A332653 Cf. A023037, A056665, A057661, A226561, A228640, A332620, A332621, A332652, A332655. %K A332653 nonn %O A332653 1,2 %A A332653 _Ilya Gutkovskiy_, Feb 18 2020