%I A135240
%S A135240 36,20575296
%N A135240 Numbers n such that phi(sigma(n))=2n.
%C A135240 No other terms below 10^10.
%e A135240 phi(sigma(20575296))=phi(71238999)=41150592=2*20575296, so 20575296 is 
               in the sequence.
%t A135240 Do[If[EulerPhi[DivisorSigma[1,n]]==2n,Print[n]],{n,350000000}]
%Y A135240 Cf. A071525, A135238, A135239.
%Y A135240 Sequence in context: A071226 A134369 A151654 this_sequence A058432 A058458 
               A077575
%Y A135240 Adjacent sequences: A135237 A135238 A135239 this_sequence A135241 A135242 
               A135243
%K A135240 bref,more,nonn
%O A135240 1,1
%A A135240 Farideh Firoozbakht (mymontain(AT)yahoo.com), Dec 26 2007
%E A135240 Search extended to 10^10 by Max Alekseyev (maxale(AT)gmail.com), Sep 
               25 2009