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%I #14 May 04 2018 00:44:24
%S 1,3,19,1013,4133,9833,30809
%N Numbers n such that 2^n + 3^n + 5^n + 7^n is a prime number.
%C All terms are odd. - _Robert Israel_, May 03 2018
%e 2^3 + 3^3 + 5^3 + 7^3 = 503 (prime), thus 3 is in the sequence.
%p select(t -> isprime(2^t+3^t+5^t+7^t), [seq(i,i=1..10000,2)]); # _Robert Israel_, May 03 2018
%t Do[If[PrimeQ[2^n+3^n+5^n+7^n], Print[n]], {n,1,5000}]
%K hard,more,nonn
%O 1,2
%A _Stefan Steinerberger_, Feb 05 2006
%E a(6) from _Ryan Propper_, Mar 24 2006
%E a(7) from Joao Carlos Leandro da Silva (zxawyh66(AT)yahoo.com), Jun 01 2009
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