%I #14 Sep 08 2022 08:46:04
%S 2,10,11,12,14,19,24,40,45,46,48,65,66,67,75,85,90,103,105,117,119,
%T 137,147,164,167,179,181,205,220,235,242,253,254,263,268,277,303,315,
%U 332,337,366,369,370,389,399,404,424,431,446,449,480,481,506,509,521,523
%N Numbers n such that (n^19-1)/(n-1) is prime.
%H Vincenzo Librandi, <a href="/A217072/b217072.txt">Table of n, a(n) for n = 1..1000</a>
%t Select[Range[2, 1000], PrimeQ[(#^19 - 1)/(# - 1)] &] (* _T. D. Noe_, Sep 26 2012 *)
%o (Magma) [n: n in [2..1000] |IsPrime((n^19 - 1) div (n - 1))]; // _Vincenzo Librandi_, Sep 28 2012
%o (PARI) is(n)=isprime((n^19-1)/(n-1)) \\ _Charles R Greathouse IV_, Feb 17 2017
%Y Cf. A002384, A049409, A100330, A162862, A217070-A217089.
%K nonn,easy
%O 1,1
%A _Tim Johannes Ohrtmann_, Sep 26 2012
%E More terms from _T. D. Noe_, Sep 26 2012