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 A216881 Primes p such that x^7 = 3 has a solution mod p. 2

%I

%S 2,3,5,7,11,13,17,19,23,31,37,41,47,53,59,61,67,73,79,83,89,97,101,

%T 103,107,109,131,137,139,149,151,157,163,167,173,179,181,191,193,199,

%U 223,227,229,233,241,251,257,263,269,271,277,283,293,307,311,313,317

%N Primes p such that x^7 = 3 has a solution mod p.

%C Complement of A042969 relative to A000040.

%C Differs from A042966 first at index 98. - _R. J. Mathar_, Mar 13 2013

%H Vincenzo Librandi, <a href="/A216881/b216881.txt">Table of n, a(n) for n = 1..1000</a>

%t ok[p_] := Reduce[Mod[x^7 - 3, p] == 0, x, Integers] =!= False; Select[Prime[Range[150]], ok]

%o (MAGMA) [p: p in PrimesUpTo(500) | exists(t){x: x in ResidueClassRing(p) | x^7 eq 3}];

%K nonn,easy

%O 1,1

%A _Vincenzo Librandi_, Sep 19 2012

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Last modified December 3 12:16 EST 2021. Contains 349462 sequences. (Running on oeis4.)