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A128337 Numbers k such that (7^k + 5^k)/12 is prime. 19
11, 31, 173, 271, 547, 1823, 2111, 5519, 7793, 22963, 41077, 49739 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
All terms are primes.
a(13) > 10^5. - Robert Price, Nov 20 2012
LINKS
MATHEMATICA
k=7; Do[p=Prime[n]; f=(k^p+5^p)/(k+5); If[ PrimeQ[f], Print[p] ], {n, 1, 100}]
PROG
(PARI) is(n)=isprime((7^n+5^n)/12) \\ Charles R Greathouse IV, Feb 17 2017
CROSSREFS
Sequence in context: A001604 A144727 A002535 * A093382 A098264 A023279
KEYWORD
hard,more,nonn
AUTHOR
Alexander Adamchuk, Feb 27 2007
EXTENSIONS
a(6)-a(12) from Robert Price, Nov 20 2012
STATUS
approved

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Last modified September 2 05:36 EDT 2024. Contains 375604 sequences. (Running on oeis4.)