A038891 Odd primes p such that 19 is a square mod p.

3, 5, 17, 19, 31, 59, 61, 67, 71, 73, 79, 101, 103, 107, 127, 137, 149, 151, 157, 167, 179, 197, 211, 223, 227, 229, 233, 277, 307, 313, 331, 349, 353, 379, 383, 389, 397, 431, 439, 457, 461, 487, 523, 541, 547

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn

Comments

Also, only entries p=1 (mod 4) of the sequence are squares mod 19 (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[100]], JacobiSymbol[19, #] != -1 &] (* Vincenzo Librandi, Sep 07 2012 *)

PARI

isok(p) = (p>2) && isprime(p) && issquare(Mod(19, p)); \\ Michel Marcus, Jun 23 2019

Extensions

Name clarified by Michel Marcus, Jun 23 2019