Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #12 Sep 08 2022 08:44:53
%S 7,13,31,37,43,61,67,73,79,103,139,157,163,193,199,211,223,229,241,
%T 331,337,349,367,379,397,433,439,457,463,499,523,541,547,571,601,607,
%U 619,631,643,673,709,727,739,751
%N Primes p such that x^3 = 19 has no solution mod p.
%C Complement of A040083 relative to A000040. - _Vincenzo Librandi_, Sep 17 2012
%H Vincenzo Librandi, <a href="/A040084/b040084.txt">Table of n, a(n) for n = 1..1000</a>
%t ok[p_]:= Reduce[Mod[x^3 - 19, p] == 0, x, Integers] == False;Select[Prime[Range[200]], ok] (* _Vincenzo Librandi_, Sep 17 2012 *)
%o (Magma) [p: p in PrimesUpTo(1000) | not exists{x : x in ResidueClassRing(p) | x^3 eq 19} ]; // _Vincenzo Librandi_, Sep 17 2012
%K nonn,easy
%O 1,1
%A _N. J. A. Sloane_.