A058602 Numbers k such that 7*2^k - 5 is prime.

0, 2, 4, 6, 8, 16, 18, 26, 30, 42, 52, 54, 60, 98, 138, 148, 164, 180, 188, 198, 232, 268, 366, 494, 556, 636, 700, 830, 908, 2164, 5764, 9854, 10384, 17550, 20236, 32820, 42372, 77466, 106562

Offset

1,2

Comments

a(36) > 30000. - Jinyuan Wang, Feb 01 2020

Links

Table of n, a(n) for n=1..39.

Mathematica

Do[ If[ PrimeQ[ 7*2^n - 5 ], Print[ n ] ], {n, 0, 5371} ]
Select[Range[0, 10000], PrimeQ[(7*2^# - 5)] &] (* Vincenzo Librandi, Sep 29 2012 *)

Prog

(PARI) is(n)=ispseudoprime(7*2^n-5) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Cf. A058595 (7*2^k + 5 is prime).

Sequence in context: A325764 A258119 A073696 * A133808 A160560 A332291

Adjacent sequences: A058599 A058600 A058601 * A058603 A058604 A058605

Keyword

nonn,more

Author

Robert G. Wilson v, Dec 26 2000

Extensions

a(31)-a(32) from Vincenzo Librandi, Sep 29 2012

a(33)-a(35) from Jinyuan Wang, Feb 01 2020

a(36)-a(37) from Michael S. Branicky, May 19 2023

a(1)=0 inserted and a(38)-a(39) from Michael S. Branicky, Jul 27 2024

Status

approved