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A057912
Numbers k such that 3*2^k - 5 is prime.
1
2, 3, 4, 7, 9, 10, 13, 15, 25, 31, 34, 48, 52, 64, 109, 145, 162, 204, 207, 231, 271, 348, 444, 553, 559, 1504, 1708, 3048, 3970, 4423, 4668, 5737, 5877, 6130, 8584, 10663, 12517, 16591, 18450, 19362, 22291, 34468, 36637, 52212, 59040, 130279, 236511, 392260, 496411, 536868, 565024, 662703, 908005
OFFSET
1,1
COMMENTS
a(44) > 44233. - Jinyuan Wang, Feb 02 2020
a(54) > 1000000 - Jon Grantham, Jul 30 2023
LINKS
Jon Grantham and Andrew Granville, Fibonacci primes, primes of the form 2^n-k and beyond, arXiv:2307.07894 [math.NT], 2023.
MATHEMATICA
Do[ If[ PrimeQ[ 3*2^n - 5 ], Print[ n ] ], {n, 1, 3000} ]
PROG
(PARI) is(n)=ispseudoprime(3*2^n-5) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
Cf. A057913 (3*2^k + 5 is prime).
Cf. A048488 (3*2^k - 5, but with different offset).
Sequence in context: A364868 A137451 A325091 * A141748 A057267 A277066
KEYWORD
nonn,more
AUTHOR
Robert G. Wilson v, Nov 16 2000
EXTENSIONS
a(36)-a(41) from Vincenzo Librandi, Oct 10 2013
a(42)-a(43) from Jinyuan Wang, Feb 02 2020
a(44)-a(45) from Michael S. Branicky, May 20 2023
a(46)-a(53) from Jon Grantham, Jul 30 2023
STATUS
approved