OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
MATHEMATICA
ok[p_]:=Reduce[Mod[x^5-20, p]==0, x, Integers]=!=False; Select[Prime[Range[150]], ok]
PROG
(Magma) [p: p in PrimesUpTo(400) | exists(t){x : x in ResidueClassRing(p) | x^5 eq 20}];
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Sep 19 2012
STATUS
approved