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A079906 Numbers k such that 5*6^k - 1 is prime. 15
1, 2, 6, 7, 11, 23, 33, 48, 68, 79, 116, 151, 205, 1016, 1332, 1448, 3481, 3566, 3665, 11233, 13363, 29166, 44358, 58530, 191706, 386450, 605168, 616879, 1204077 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
a(29) > 618000. - Karsten Bonath, Nov 04 2019
REFERENCES
R. K. Guy, Unsolved Problems in Theory of Numbers, Section A3.
LINKS
H. C. Williams, The primality of certain integers of the form 2Ar^n - 1, Acta Arith. 39 (1981), 7-17.
MATHEMATICA
Do[ If[ PrimeQ[5*6^n - 1], Print[n]], {n, 1, 5000}]
PROG
(PARI) for(n=1, 2000, if(isprime(5*6^n-1), print1(n, ", ")))
CROSSREFS
Sequence in context: A241720 A224082 A051678 * A226814 A233419 A189327
KEYWORD
nonn,hard,more
AUTHOR
Robert G. Wilson v, Jan 16 2003
EXTENSIONS
a(20)-a(24) from Donovan Johnson, Nov 26 2008
a(25) from Robert Price, Jan 23 2016
a(26) from Karsten Bonath, Jul 01 2019
a(27) from Karsten Bonath, Oct 29 2019
a(28) from Karsten Bonath, Nov 04 2019
a(29) from Ryan Propper, Nov 21 2023
STATUS
approved

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Last modified March 19 06:05 EDT 2024. Contains 370952 sequences. (Running on oeis4.)