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A217131
Numbers n such that 7^n - 8 is prime.
10
2, 4, 8, 10, 50, 106, 182, 293, 964, 1108, 1654, 1756, 4601, 8870, 15100, 17446, 22742, 34570, 50150, 95276
OFFSET
1,1
COMMENTS
a(21) > 10^5. - Robert Price, Jan 23 2014
MATHEMATICA
Select[Range[1, 5000], PrimeQ[7^# - 8] &]
PROG
(PARI) for(n=1, 5*10^3, if(isprime(7^n-8), print1(n, ", ")))
KEYWORD
nonn
AUTHOR
Vincenzo Librandi, Oct 01 2012
EXTENSIONS
a(14)-a(20) from Robert Price, Jan 23 2014
STATUS
approved