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 A174651 #17 Oct 05 2019 10:21:00
%S A174651 1,88,125,5246
%N A174651 Numbers n such that Sum_{k=1..n} k*Mobius(k) = n.
%C A174651 No more terms < 10^7.
%t A174651 muSums = Accumulate@Table[MoebiusMu[k] k, {k, 10^7}]; A174651 = {}; For[i = 1, i <= Length@muSums, i++, If[muSums[[i]] == i, AppendTo[A174651, i]]]; A174651
%t A174651 smQ[x_]:=x==Total[Table[n*MoebiusMu[n],{n,x}]]; Select[Range[6000],smQ] (* _Harvey P. Dale_, Oct 05 2019 *)
%Y A174651 Cf. A008683, A002321, A055615, A068340.
%K A174651 nonn
%O A174651 1,2
%A A174651 _Carl Najafi_, Dec 22 2012