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 A332686 #12 Mar 13 2021 10:05:27
%S A332686 1,2,3,5,7,9,13,18,21,23,33,33,47,49,51,67,81,76,103,97,103,119,151,
%T A332686 135,163,173,185,189,243,185,279,280,265,299,291,291,397,379,369,371,
%U A332686 491,381,543,491,455,553,651,539,653,610,643,683,831,689,743,753,801,887,1029
%N A332686 a(n) = Sum_{k=1..n} phi(k/gcd(n, k)).
%C A332686 Inverse Moebius transform of A053570.
%H A332686 Seiichi Manyama, <a href="/A332686/b332686.txt">Table of n, a(n) for n = 1..10000</a>
%F A332686 a(n) = Sum_{k=1..n} phi(lcm(n, k)/n).
%F A332686 a(n) = Sum_{d|n} A053570(d).
%t A332686 Table[Sum[EulerPhi[k/GCD[n, k]], {k, 1, n}], {n, 1, 59}]
%o A332686 (PARI) a(n) = sum(k=1, n, eulerphi(k/gcd(n, k))); \\ _Michel Marcus_, Feb 21 2020
%Y A332686 Cf. A000010, A002088, A029935, A029939, A053570, A332685.
%K A332686 nonn
%O A332686 1,2
%A A332686 _Ilya Gutkovskiy_, Feb 19 2020