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A128351
Numbers k such that (16^k - 5^k)/11 is prime.
18
7, 13, 109, 139, 967, 60013, 97613
OFFSET
1,1
COMMENTS
All terms are primes.
a(8) > 10^5. - Robert Price, Jul 03 2013
MATHEMATICA
k=16; Do[p=Prime[n]; f=(k^p-5^p)/(k-5); If[ PrimeQ[f], Print[p] ], {n, 1, 100}]
PROG
(PARI) is(n)=isprime((16^n-5^n)/11) \\ Charles R Greathouse IV, Feb 17 2017
KEYWORD
hard,more,nonn
AUTHOR
Alexander Adamchuk, Feb 27 2007
EXTENSIONS
a(6)-a(7) from Robert Price, Jul 03 2013
STATUS
approved