A051079 - OEIS

%I #18 Sep 08 2022 08:44:59

%S 2,3,19,43,59,67,73,83,89,107,113,139,163,179,227,233,251,257,283,307,

%T 337,347,353,379,419,443,467,499,523,547,563,571,577,587,593,617,619,

%U 643,659,683,739,787,827,859,883,907,937,947,971,1019,1033,1049,1097,1123

%N Primes p such that x^20 = -2 has a solution mod p.

%C Complement of A216741 relative to A000040. - _Vincenzo Librandi_, Sep 16 2012

%H Vincenzo Librandi, <a href="/A051079/b051079.txt">Table of n, a(n) for n = 1..1000</a>

%t ok[p_]:= Reduce[Mod[x^20 + 2, p] == 0, x, Integers] =!= False; Select[Prime[Range[400]], ok] (* _Vincenzo Librandi_, Sep 15 2012 *)

%o (PARI) /* see A051071 */

%o (Magma) [p: p in PrimesUpTo(1150) | exists(t){x : x in ResidueClassRing(p) | x^20 eq - 2}]; // _Vincenzo Librandi_, Sep 15 2012

%K nonn,easy

%O 1,1

%A _N. J. A. Sloane_

%E More terms from _Joerg Arndt_, Jul 27 2011