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