A180644 - OEIS

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A180644

Numbers n such that 3+phi(n)^2 is a prime

%I #2 Mar 30 2012 17:35:07

%S 3,4,5,6,8,10,11,12,15,16,20,22,23,24,29,30,46,53,58,71,85,106,107,

%T 113,128,131,136,141,142,145,160,170,173,179,187,188,192,204,205,213,

%U 214,226,232,240,257,262,282,284,290,317,328,346,348,352,358,374,400,410

%N Numbers n such that 3+phi(n)^2 is a prime

%e a(15)=29 since 3+phi(29)^2=3+28^2=787 is prime

%Y Cf. A000010

%K nonn

%O 1,1

%A _Carmine Suriano_, Sep 14 2010