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Phi(n)*sigma(n)+1 is prime.
0

%I #5 Mar 30 2012 18:38:51

%S 1,8,9,10,12,15,20,28,30,32,35,36,42,45,50,54,58,60,70,80,92,93,95,

%T 100,110,114,122,123,124,125,130,132,142,143,145,152,155,162,165,168,

%U 169,171,172,174,175,176,178,180,183,185,186,195,198,200,204,209,212,216

%N Phi(n)*sigma(n)+1 is prime.

%K nonn

%O 1,2

%A _Benoit Cloitre_, Feb 04 2002