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%I #14 Sep 08 2022 08:46:04
%S 2,14,19,31,44,53,71,82,117,127,131,145,177,197,203,241,258,261,276,
%T 283,293,320,325,379,387,388,406,413,461,462,470,486,491,534,549,569,
%U 582,612,618,639,696,706,723,746,765,767,774,796,802,877,878,903,923,981
%N Numbers n such that (n^31-1)/(n-1) is prime.
%H Vincenzo Librandi, <a href="/A217075/b217075.txt">Table of n, a(n) for n = 1..1000</a>
%t Select[Range[2, 1000], PrimeQ[(#^31 - 1)/(# - 1)] &] (* _T. D. Noe_, Sep 26 2012 *)
%o (Magma) [n: n in [2..1000] |IsPrime((n^31 - 1) div (n - 1))]; // _Vincenzo Librandi_, Sep 28 2012
%o (PARI) is(n)=isprime((n^31-1)/(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
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