OFFSET
1,1
COMMENTS
a(21) > 10^5.
MATHEMATICA
Select[Range[1, 100000], PrimeQ[7^# - 12] &]
PROG
(PARI) for(n=1, 5*10^5, if(isprime(7^n-12), print1(n, ", ")))
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert Price, Jan 23 2014
STATUS
approved