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 A332620 #13 Sep 08 2022 08:46:25
%S A332620 1,6,57,532,12505,93786,4941265,67117128,2324524401,40000400110,
%T A332620 2853116706121,35664407810076,3634501279107049,66672041585829330,
%U A332620 3503151123049919265,147573952606856413456,13235844190181388226849,236078448452969449231206,35611553801885644604231641
%N A332620 a(n) = Sum_{k=1..n} n^(n/gcd(n, k)).
%H A332620 Seiichi Manyama, <a href="/A332620/b332620.txt">Table of n, a(n) for n = 1..385</a>
%F A332620 a(n) = [x^n] Sum_{k>=1} Sum_{j>=1} phi(j) * n^j * x^(k*j).
%F A332620 a(n) = Sum_{k=1..n} n^(lcm(n, k)/k).
%F A332620 a(n) = Sum_{d|n} phi(d) * n^d.
%F A332620 a(n) = n * A332621(n).
%t A332620 Table[Sum[n^(n/GCD[n, k]), {k, 1, n}], {n, 1, 19}]
%t A332620 Table[Sum[EulerPhi[d] n^d, {d, Divisors[n]}], {n, 1, 19}]
%t A332620 Table[SeriesCoefficient[Sum[Sum[EulerPhi[j] n^j x^(k j), {j, 1, n}], {k, 1, n}], {x, 0, n}], {n, 1, 19}]
%o A332620 (Magma) [&+[n^(n div Gcd(n,k)):k in [1..n]]:n in [1..20]]; // _Marius A. Burtea_, Feb 17 2020
%o A332620 (PARI) a(n) = sum(k=1, n, n^(n/gcd(n, k))); \\ _Michel Marcus_, Mar 10 2021
%Y A332620 Cf. A000010, A056665, A066108, A226561, A228640, A321349, A332621.
%K A332620 nonn
%O A332620 1,2
%A A332620 _Ilya Gutkovskiy_, Feb 17 2020