A040130 Primes p such that x^4 = 15 has a solution mod p.

2, 3, 5, 7, 11, 43, 53, 59, 61, 67, 71, 103, 109, 113, 127, 131, 137, 163, 179, 181, 191, 223, 239, 241, 251, 257, 283, 307, 311, 317, 349, 359, 367, 419, 431, 463, 479, 487, 491, 523, 541, 547, 557, 593, 599, 607

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Links

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

Programs

Magma

[p: p in PrimesUpTo(800) | exists(t){x : x in ResidueClassRing(p) | x^4 eq 15}]; // Vincenzo Librandi, Sep 12 2012

Mathematica

ok [p_]:=Reduce[Mod[x^4 - 15, p]== 0, x, Integers]=!= False; Select[Prime[Range[180]], ok] (* Vincenzo Librandi, Sep 12 2012 *)