A040147 Primes p such that x^4 = 20 has a solution mod p.
2, 5, 11, 19, 29, 31, 59, 61, 71, 79, 131, 139, 151, 179, 191, 199, 211, 229, 239, 251, 271, 311, 331, 349, 359, 379, 401, 409, 419, 421, 431, 439, 449, 479, 491, 499, 509, 521, 569, 571, 599, 619, 631, 659, 661
Offset: 1
Links
- Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Crossrefs
Cf. A040148.
Programs
-
Magma
[p: p in PrimesUpTo(800) | exists(t){x : x in ResidueClassRing(p) | x^4 eq 20}]; // Vincenzo Librandi, Sep 12 2012 -
Mathematica
ok [p_]:=Reduce[Mod[x^4 - 20, p]== 0, x, Integers]=!= False; Select[Prime[Range[180]], ok] (* Vincenzo Librandi, Sep 12 2012 *)