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URL: https://oeis.org/A059077

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A059077
Numbers k such that 2*7^k - 3 is prime.
0
1, 3, 4, 7, 132, 253, 9040, 21888
OFFSET
1,2
COMMENTS
a(9) > 27376. - Jinyuan Wang, Dec 21 2019
a(9) > 60000. - Michael S. Branicky, Jul 10 2024
MATHEMATICA
Do[ If[ PrimeQ[ 2*7^n - 3 ], Print[n] ], {n, 1, 6000} ]
PROG
(PARI) is(n)=ispseudoprime(2*7^n-3) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
Cf. A059041 (3*7^k+2 is prime).
Sequence in context: A042543 A041987 A100978 * A042707 A229348 A215758
KEYWORD
nonn,more
AUTHOR
Robert G. Wilson v, Feb 12 2001
EXTENSIONS
a(7)-a(8) from Jinyuan Wang, Dec 21 2019
STATUS
approved