A058593 Numbers k such that 7*2^k - 3 is prime.

1, 3, 4, 8, 9, 12, 15, 19, 23, 24, 33, 75, 92, 128, 139, 140, 167, 235, 284, 504, 524, 779, 804, 912, 1104, 1439, 4680, 4875, 5843, 9033, 9320, 13168, 14305, 15800, 16192, 24135, 26728, 47535, 50215, 52227, 54612, 66433, 69940, 79640, 79939, 117988

Offset

1,2

Comments

a(38) > 43035. - Jinyuan Wang, Jan 20 2020

Links

Table of n, a(n) for n=1..46.

Mathematica

Do[ If[ PrimeQ[ 7*2^n - 3 ], Print[ n ] ], {n, 1, 5222} ]
Select[Range[0, 10000], PrimeQ[(7 2^# - 3)] &] (* Vincenzo Librandi, Sep 29 2012 *)

Prog

(PARI) is(n)=ispseudoprime(7*2^n-3) \\ Charles R Greathouse IV, Jun 12 2017

Crossrefs

Cf. A058592 (7*2^k + 3 is prime).

Sequence in context: A286750 A359376 A135135 * A374046 A310017 A191285

Adjacent sequences: A058590 A058591 A058592 * A058594 A058595 A058596

Keyword

nonn,more

Author

Robert G. Wilson v, Dec 26 2000

Extensions

a(29)-a(31) from Vincenzo Librandi, Sep 29 2012

a(32)-a(37) from Jinyuan Wang, Jan 20 2020

a(38)-a(41) from Michael S. Branicky, Mar 18 2024

a(42)-a(46) from Michael S. Branicky, Oct 23 2024

Status

approved