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A128349 Numbers k such that (13^k - 5^k)/8 is prime. 18
5, 19, 71, 197, 659, 22079, 61949 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
All terms are primes.
a(8) > 10^5. - Robert Price, Mar 05 2013
LINKS
MATHEMATICA
k=13; Do[p=Prime[n]; f=(k^p-5^p)/(k-5); If[ PrimeQ[f], Print[p] ], {n, 1, 100}]
PROG
(PARI) is(n)=isprime((13^n-5^n)/8) \\ Charles R Greathouse IV, Feb 17 2017
CROSSREFS
Sequence in context: A243413 A222538 A095073 * A255449 A296630 A001834
KEYWORD
hard,more,nonn
AUTHOR
Alexander Adamchuk, Feb 27 2007
EXTENSIONS
a(6)-a(7) from Robert Price, Mar 05 2013
STATUS
approved

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Last modified July 25 01:41 EDT 2024. Contains 374585 sequences. (Running on oeis4.)