OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
MATHEMATICA
ok[p_]:= Reduce[Mod[x^20 + 2, p] == 0, x, Integers] == False; Select[Prime[Range[100]], ok]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Sep 15 2012
STATUS
approved