|
%I #13 Feb 17 2017 14:25:52
%S 2,14,26,4646,68484
%N Numbers n such that 5^n-n^5 is prime.
%H Henri & Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=5%5En-n%5E5">PRP Records.</a>
%e a(1)=2 because 2^5 - 5^2 = 7 is prime
%t Do[If[PrimeQ[(5^n-n^5)],Print[n]],{n,1,5000}]
%o (PARI) is(n)=isprime(5^n-n^5) \\ _Charles R Greathouse IV_, Feb 17 2017
%K hard,more,nonn
%O 1,1
%A Mohammed Bouayoun (Mohammed.Bouayoun(AT)sanef.com), Apr 13 2006, Jan 08 2008
%E a(5) found by _Donovan Johnson_
%E First five terms confirmed by _Dmitry Kamenetsky_, Dec 18 2008
|
