%I
%S 707,7843,143591,274211,598787,737807,861749,928421,1515521,1682203,
%T 1936099,2223143,2709473,2908373,2985641,3669919,3689279,3825419,
%U 3848851,4154297,4429159,5321743,5654623,5678131,6548899,8916427,11403743,11474267,12191803,13340869
%N Numbers n such that sigma(sigma(n)  phi(n)) = phi(n).
%e sigma(sigma(707)phi(707)) = sigma(816600) = sigma(216) = 600 = phi(707), so 707 is a term of the sequence.
%t Select[Range[2, 10^6], DivisorSigma[1, DivisorSigma[1, # ]  EulerPhi[ # ]] == EulerPhi[ # ] &]
%K nonn
%O 1,1
%A _Joseph L. Pe_, Sep 12 2002
%E a(9)a(30) from _Donovan Johnson_, Jan 19 2012
