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A059749
Numbers k such that 5*2^k - 7 is prime.
1
1, 2, 4, 6, 10, 16, 30, 32, 52, 68, 78, 84, 118, 136, 154, 406, 488, 696, 752, 880, 2754, 3922, 3976, 4888, 5866, 51084, 55744, 61000, 121188, 122608
OFFSET
1,2
COMMENTS
The next terms are > 50000. - Jinyuan Wang, Feb 03 2020
MATHEMATICA
Do[ If[ PrimeQ[ 5*2^n - 7 ], Print[n] ], {n, 3000} ]
Select[Range[6000], PrimeQ[(5*2^# - 7)] &] (* Vincenzo Librandi, Sep 30 2012 *)
PROG
(PARI) is(n)=ispseudoprime(5*2^n-7) \\ Charles R Greathouse IV, Jun 13 2017
(PFGW) ABC2 5*2^$a-7
a: from 1 to 10000 // Jinyuan Wang, Feb 03 2020
CROSSREFS
Cf. A059748 (5*2^k + 7 is prime).
Sequence in context: A018161 A288599 A067880 * A334213 A164142 A048833
KEYWORD
nonn,more
AUTHOR
Robert G. Wilson v, Feb 10 2001
EXTENSIONS
a(22)-a(25) from Vincenzo Librandi, Sep 30 2012
a(26)-a(28) from Michael S. Branicky, May 20 2023
a(29)-a(30) from Michael S. Branicky, Jul 27 2024
STATUS
approved