A038906 Primes p such that 31 is not a square mod p.

7, 13, 17, 19, 29, 37, 47, 53, 59, 61, 67, 71, 73, 89, 103, 107, 131, 137, 163, 181, 191, 197, 211, 227, 229, 241, 269, 277, 283, 307, 311, 313, 337, 353, 359, 379, 389, 401, 409, 419, 431, 433, 439, 443, 449, 457

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn

Comments

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

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Programs

Mathematica

Select[Prime@Range[120], JacobiSymbol[31, #] == -1 &] (* Vincenzo Librandi, Sep 09 2012 *)

Extensions

Offset changed from 0 to 1 by Vincenzo Librandi, Sep 09 2012