A058595 Numbers k such that 7*2^k + 5 is prime.

1, 3, 5, 11, 13, 61, 115, 653, 889, 957, 997, 1013, 1421, 2329, 2675, 4795, 5755, 7059, 7405, 7613, 7973, 9445, 23467, 31769, 32417

Offset

1,2

Comments

a(24) > 30000. - Jinyuan Wang, Feb 01 2020

Links

Table of n, a(n) for n=1..25.

Mathematica

Do[ If[ PrimeQ[ 7*2^n + 5 ], Print[ n ] ], {n, 1, 6800} ]
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. A058602 (7*2^k - 5 is prime).

Sequence in context: A162876 A162875 A166564 * A154773 A176658 A086284

Adjacent sequences: A058592 A058593 A058594 * A058596 A058597 A058598

Keyword

nonn,more

Author

Robert G. Wilson v, Dec 26 2000

Extensions

a(18)-a(22) from Vincenzo Librandi, Sep 29 2012

a(23) from Jinyuan Wang, Feb 01 2020

a(24)-a(25) from Michael S. Branicky, May 19 2023

Status

approved