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A128350
Numbers k such that (14^k - 5^k)/9 is prime.
18
2, 151, 673, 709, 2999, 17909, 77213
OFFSET
1,1
COMMENTS
All terms are primes.
a(8) > 10^5. - Robert Price, Apr 23 2013
MATHEMATICA
k=14; Do[p=Prime[n]; f=(k^p-5^p)/(k-5); If[ PrimeQ[f], Print[p] ], {n, 1, 200}]
PROG
(PARI) is(n)=isprime((14^n-5^n)/9) \\ Charles R Greathouse IV, Feb 17 2017
KEYWORD
hard,more,nonn
AUTHOR
Alexander Adamchuk, Feb 27 2007
EXTENSIONS
One more term from Herman Jamke (hermanjamke(AT)fastmail.fm), May 01 2008
a(6) and a(7) from Robert Price, Apr 23 2013
STATUS
approved