A128347 - OEIS

A128347

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

5, 41, 149, 229, 263, 739, 3457, 20269, 98221

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OFFSET

1,1

COMMENTS

All terms are primes.

a(10) > 10^5. - Robert Price, Jan 24 2013

LINKS

MATHEMATICA

k=11; Do[p=Prime[n]; f=(k^p-5^p)/(k-5); If[ PrimeQ[f], Print[p] ], {n, 1, 100}]

PROG

(PARI) is(n)=isprime((11^n-5^n)/6) \\ Charles R Greathouse IV, Feb 17 2017

CROSSREFS

KEYWORD

hard,more,nonn

AUTHOR

EXTENSIONS

a(7)-a(9) from Robert Price, Jan 24 2013

STATUS

approved