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%I #17 Jun 11 2021 08:40:53
%S 2,6,20,24,18582,20366
%N Numbers k such that absolute value of 7^k - k^7 is prime.
%t lst={};k=7;Do[If[PrimeQ[Abs[k^n-n^k]], AppendTo[lst, n]], {n, 0, 10^4}];lst (* _Vladimir Joseph Stephan Orlovsky_, Sep 10 2008 *)
%o (PARI) is(n)=isprime(abs(7^n-n^7)) \\ _Charles R Greathouse IV_, Feb 17 2017
%Y Cf. A072180, A109387, A117705, A117706, A128448, A128449, A128450, A128451, A122003, A128453, A128454.
%K nonn,hard,more
%O 1,1
%A _Alexander Adamchuk_, Mar 03 2007
%E a(5) and a(6) from _Donovan Johnson_, Mar 03 2008
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