A128336 - OEIS

A128336

Numbers k such that (6^k + 5^k)/11 is prime.

3, 5, 17, 397, 409, 643, 1783, 2617, 4583, 8783

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OFFSET

1,1

COMMENTS

All terms are primes.

No other terms less than 100000. - Robert Price, May 11 2012

LINKS

MATHEMATICA

k=6; Do[p=Prime[n]; f=(k^p+5^p)/(k+5); If[ PrimeQ[f], Print[p] ], {n, 1, 100}]

PROG

(PARI) forprime(p=3, 1e4, if(ispseudoprime((6^p+5^p)/11), print1(p", "))) \\ Charles R Greathouse IV, Jul 16 2011

CROSSREFS

KEYWORD

hard,more,nonn

AUTHOR

EXTENSIONS

a(7)-a(9) from Alexander Adamchuk, May 04 2010

One more term (8783) added (unknown discoverer) corresponding to a probable prime with 6834 digits by Jean-Louis Charton, Oct 06 2010

STATUS

approved