OFFSET
1,1
COMMENTS
a(22) > 10^5. - Robert Price, May 04 2016
MATHEMATICA
Select[Range[12, 100000], PrimeQ[7^# - 6^(# + 1)] &]
PROG
(PARI) is(n)=ispseudoprime(7^n-6^(n+1)) \\ Charles R Greathouse IV, Jun 08 2016
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Robert Price, Jun 04 2016
STATUS
approved