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A128450
Numbers k such that absolute value of 10^k - k^10 is prime.
9
3, 9, 273, 399
OFFSET
1,1
MATHEMATICA
lst={}; k=10; Do[If[PrimeQ[Abs[k^n-n^k]], AppendTo[lst, n]], {n, 0, 10^4}]; lst (* Vladimir Joseph Stephan Orlovsky, Sep 10 2008 *)
Select[Range[0, 10000], PrimeQ[10^# - #^10] &] (* Vincenzo Librandi, Apr 01 2015 *)
PROG
(Magma) [n: n in [0..500]| IsPrime(10^n-n^10)]; // Vincenzo Librandi, Apr 01 2015
(PARI) is(n)=isprime(abs(10^n-n^10)) \\ Charles R Greathouse IV, Feb 17 2017
KEYWORD
hard,more,nonn,less
AUTHOR
Alexander Adamchuk, Mar 03 2007
STATUS
approved