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Primes p such that 91 is not a square mod p.
1

%I #10 Sep 08 2022 08:44:53

%S 2,17,19,23,31,37,43,47,59,61,79,83,101,107,109,127,137,149,157,167,

%T 173,179,181,191,193,197,211,223,227,257,263,269,271,281,307,313,317,

%U 347,383,401,421,433,443,449,457

%N Primes p such that 91 is not a square mod p.

%H Vincenzo Librandi, <a href="/A038980/b038980.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Prime[Range[120]], JacobiSymbol[91, #]==-1 &] (* _Vincenzo Librandi_, Sep 10 2012 *)

%o (Magma) [2] cat [p: p in PrimesUpTo(457) | not IsSquare(R! 91) where R:= ResidueClassRing(p)]; // _Vincenzo Librandi_, Sep 10 2012

%K nonn,easy

%O 1,1

%A _N. J. A. Sloane_.

%E Offset changed from 0 to 1 by _Vincenzo Librandi_, Sep 10 2012