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%I #7 Sep 08 2022 08:45:02
%S 191,229,419,457,571,647,761,1217,1483,1559,1597,1787,1901,2053,2129,
%T 2243,2281,2357,2699,2851,2927,3041,3079,3307,3877,4219,4409,4447,
%U 4523,4561,4637,4751,4789,4903,5701,6271,6689,6803,6841,6917,7069,7297,7411
%N Primes p such that x^19 = 2 has no solution mod p.
%C Complement of A049551 relative to A000040.
%H Vincenzo Librandi, <a href="/A059244/b059244.txt">Table of n, a(n) for n = 1..1000</a>
%t ok[p_]:= Reduce[Mod[x^19 - 2, p] == 0, x, Integers] == False;Select[Prime[Range[4000]], ok] (* _Vincenzo Librandi_, Sep 20 2012 *)
%o (Magma) [p: p in PrimesUpTo(7500) | not exists{x : x in ResidueClassRing(p) | x^19 eq 2} ]; // _Vincenzo Librandi_, Sep 20 2012
%Y Cf. A000040, A049551.
%K easy,nonn
%O 1,1
%A _Klaus Brockhaus_, Jan 21 2001