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%I #9 Sep 08 2022 08:44:53
%S 5,7,11,13,17,23,29,37,41,43,47,53,61,73,83,89,97,109,113,131,137,139,
%T 163,173,181,191,193,197,199,239,241,251,257,263,269,271,281,283,293,
%U 311,317,337,347,353,359,367,373
%N Primes p such that x^4 = 19 has no solution mod p.
%C Complement of A040145 relative to A000040. - _Vincenzo Librandi_, Sep 18 2012
%H Vincenzo Librandi, <a href="/A040146/b040146.txt">Table of n, a(n) for n = 1..1000</a>
%t ok[p_]:= Reduce[Mod[x^4 - 19, p] == 0, x, Integers] == False; Select[Prime[Range[100]], ok] (* _Vincenzo Librandi_, Sep 18 2012 *)
%o (Magma) [p: p in PrimesUpTo(500) | not exists{x : x in ResidueClassRing(p) | x^4 eq 19} ]; // _Vincenzo Librandi_, Sep 18 2012
%K nonn,easy
%O 1,1
%A _N. J. A. Sloane_.
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