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Primes p such that x^56 = -2 has no solution mod p.
2

%I #7 Sep 08 2022 08:46:03

%S 5,7,13,17,23,29,31,37,41,43,47,53,61,71,73,79,89,97,101,103,109,113,

%T 127,137,149,151,157,167,173,181,191,193,197,199,211,223,229,233,239,

%U 241,263,269,271,277,281,293,311,313,317,337,349,353,359,367,373

%N Primes p such that x^56 = -2 has no solution mod p.

%C Complement of A051097 relative to A000040.

%H Vincenzo Librandi, <a href="/A216773/b216773.txt">Table of n, a(n) for n = 1..1000</a>

%t ok[p_] := Reduce[Mod[x^56 + 2, p] == 0, x, Integers] == False;Select[Prime[Range[200]], ok]

%o (Magma) [p: p in PrimesUpTo(600) | not exists{x: x in ResidueClassRing(p) | x^56 eq -2} ];

%Y Cf. A000040. A051097.

%K nonn,easy

%O 1,1

%A _Vincenzo Librandi_, Sep 16 2012