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Numbers n such that 3^n + phi(n) is prime.
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%I #4 Oct 02 2013 15:12:47

%S 3,4,10,20,44,60,583,677,947,1182,12048,16018,74316

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

%C All terms correspond to certified primes (Primo 2.2.0 beta). No more terms through 10000.

%C a(14) > 10^5. [From _Donovan Johnson_, Feb 06 2010]

%t Do[If[PrimeQ[3^n + EulerPhi[n]], Print[n]], {n, 1, 10000}]

%K hard,nonn

%O 1,1

%A _Ryan Propper_, Aug 31 2005

%E a(11)-a(13) from _Donovan Johnson_, Feb 06 2010