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A181141 Numbers k such that (8^k + 7^k)/15 is prime. 16
7, 13, 31, 43, 269, 353, 383, 619, 829, 877, 4957, 5711, 8317, 21739, 24029, 38299 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Terms 21739 and 24029 were found by Lelio R. Paula in February and April 2009. Term 38299 was found by Jean-Louis Charton in October 2010 corresponding to a probable prime with 34587 digits.

a(17) > 10^5. - Robert Price, Dec 29 2012

LINKS

Table of n, a(n) for n=1..16.

Top probable primes of form (8^n+7^n)/15

PROG

(PARI) is(n)=isprime((8^n+7^n)/15) \\ Charles R Greathouse IV, Feb 17 2017

CROSSREFS

See also A062574.

Sequence in context: A085104 A162652 A306889 * A031158 A301683 A091431

Adjacent sequences:  A181138 A181139 A181140 * A181142 A181143 A181144

KEYWORD

hard,nonn

AUTHOR

Jean-Louis Charton, Oct 06 2010

STATUS

approved

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Last modified May 25 22:17 EDT 2019. Contains 323576 sequences. (Running on oeis4.)