A049570 - OEIS

%I #15 Sep 08 2022 08:44:58

%S 2,7,17,23,31,41,47,71,73,79,89,97,103,113,127,137,151,167,193,199,

%T 223,233,239,241,257,263,271,281,311,313,337,353,359,367,383,401,409,

%U 431,433,439,449,463,479,487,503,521,569,577,593,599,601,607,617,631,641

%N Primes p such that x^38 = 2 has a solution mod p.

%C Complement of A059350 relative to A000040. - _Vincenzo Librandi_, Sep 14 2012

%H R. J. Mathar, <a href="/A049570/b049570.txt">Table of n, a(n) for n = 1..1000</a>

%H <a href="/index/Pri#smp">Index entries for related sequences</a>

%t ok[p_]:= Reduce[Mod[x^38 - 2, p] == 0, x, Integers] =!= False; Select[Prime[Range[200]], ok] (* _Vincenzo Librandi_, Sep 14 2012 *)

%o (Magma) [p: p in PrimesUpTo(700) | exists(t){x : x in ResidueClassRing(p) | x^38 eq 2}]; // _Vincenzo Librandi_, Sep 14 2012

%Y Cf. A000040, A059350.

%K nonn,easy

%O 1,1

%A _N. J. A. Sloane_