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Primes p such that 31 is not a square mod p.
2

%I #9 Sep 09 2012 03:26:34

%S 7,13,17,19,29,37,47,53,59,61,67,71,73,89,103,107,131,137,163,181,191,

%T 197,211,227,229,241,269,277,283,307,311,313,337,353,359,379,389,401,

%U 409,419,431,433,439,443,449,457

%N Primes p such that 31 is not a square mod p.

%C Also, only entries p=1 (mod 4) of the sequence are not squares mod 31 (from the quadratic reciprocity law). - _Lekraj Beedassy_, Jul 21 2004

%H Vincenzo Librandi, <a href="/A038906/b038906.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Prime@Range[120], JacobiSymbol[31, #] == -1 &] (* _Vincenzo Librandi_, Sep 09 2012 *)

%K nonn

%O 1,1

%A _N. J. A. Sloane_.

%E Offset changed from 0 to 1 by _Vincenzo Librandi_, Sep 09 2012