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 A332685 #8 Feb 21 2020 12:30:49
%S A332685 1,2,1,2,0,2,0,0,-1,0,0,0,-1,-2,-2,-3,0,-4,-1,-5,-4,-2,0,-8,-3,-4,-4,
%T A332685 -7,0,-8,-2,-10,-5,-4,-4,-13,0,-5,-4,-13,1,-15,-1,-9,-10,-5,-1,-22,-4,
%U A332685 -12,-5,-11,-1,-19,-6,-17,-6,-4,1,-28,0,-8,-12,-18,-6,-19,0,-12,-5,-17
%N A332685 a(n) = Sum_{k=1..n} mu(k/gcd(n, k)).
%C A332685 Inverse Moebius transform of A112399.
%H A332685 Ilya Gutkovskiy, <a href="/A332685/a332685.jpg">Scatterplot of a(n) up to n=10000</a>
%F A332685 a(n) = Sum_{k=1..n} mu(lcm(n, k)/n).
%F A332685 a(n) = Sum_{d|n} A112399(d).
%t A332685 Table[Sum[MoebiusMu[k/GCD[n, k]], {k, 1, n}], {n, 1, 70}]
%o A332685 (PARI) a(n) = sum(k=1, n, moebius(k/gcd(n, k))); \\ _Michel Marcus_, Feb 21 2020
%Y A332685 Cf. A002321, A007431, A007947, A008683, A063659, A112399, A276833, A304575.
%K A332685 sign
%O A332685 1,2
%A A332685 _Ilya Gutkovskiy_, Feb 19 2020