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%I A040086 #12 Sep 08 2022 08:44:53
%S A040086 13,31,37,43,67,73,79,103,109,139,157,163,181,199,211,223,229,241,271,
%T A040086 277,283,307,313,331,337,349,367,379,397,409,421,433,439,463,487,499,
%U A040086 547,601,607,613,631,661,673,727
%N A040086 Primes p such that x^3 = 20 has no solution mod p.
%C A040086 Complement of A040085 relative to A000040. - _Vincenzo Librandi_, Sep 17 2012
%H A040086 Vincenzo Librandi, <a href="/A040086/b040086.txt">Table of n, a(n) for n = 1..1000</a>
%t A040086 ok[p_]:= Reduce[Mod[x^3 - 20, p] == 0, x, Integers] == False;Select[Prime[Range[200]], ok] (* _Vincenzo Librandi_, Sep 17 2012  *)
%o A040086 (Magma) [p: p in PrimesUpTo(1000) | not exists{x : x in ResidueClassRing(p) | x^3 eq 20} ]; // _Vincenzo Librandi_, Sep 17 2012
%K A040086 nonn,easy
%O A040086 1,1
%A A040086 _N. J. A. Sloane_.

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