OFFSET
1,2
COMMENTS
a(7) > 10^5. - Robert Price, Mar 25 2014
MATHEMATICA
Select[Range[0, 5000], PrimeQ[19^# + #^19 - 1] &]
PROG
(PARI) is(n)=ispseudoprime(19^n+n^19-1) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Vincenzo Librandi, Sep 07 2012
EXTENSIONS
a(6) from Robert Price, Mar 25 2014
STATUS
approved