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 A135239 #15 Oct 13 2023 07:51:25
%S A135239 1209,27474741,55385589,222850677
%N A135239 Numbers m such that sigma(phi(m)) = 2*m.
%C A135239 From _Max Alekseyev_, Oct 12 2023: (Start)
%C A135239 No other terms below 3*10^11.
%C A135239 If a term m is odd, then phi(m) belongs to A001229; otherwise phi(m) belongs to A135240. (End)
%e A135239 sigma(phi(222850677)) = sigma(118879488) = 445701354 = 2*222850677, so 222850677 is in the sequence.
%t A135239 Do[If[DivisorSigma[1,EulerPhi[n]]==2n,Print[n]],{n,420000000}]
%Y A135239 Cf. A001229, A018784, A135240.
%K A135239 more,nonn
%O A135239 1,1
%A A135239 _Farideh Firoozbakht_, Dec 26 2007