A057913 Numbers k such that 3*2^k + 5 is prime.

1, 2, 3, 4, 5, 6, 7, 8, 14, 16, 19, 22, 24, 27, 29, 32, 38, 54, 57, 60, 76, 94, 132, 139, 175, 187, 208, 230, 379, 384, 632, 1040, 1188, 1359, 1553, 1734, 1768, 1925, 2492, 3272, 3537, 3949, 4647, 5869, 6473, 7036, 8550, 9459, 9784, 15440, 15507, 15637, 16400, 42045

Offset: 1

Author

Robert G. Wilson v, Nov 16 2000

Keywords

• nonn

Comments

a(79) > 10^6 per Grantham and Granville link, Section 6. - Michael S. Branicky, Sep 07 2024

Links

• Jon Grantham, Table of n, a(n) for n = 1..78
• Jon Grantham and Andrew Granville, Fibonacci primes, primes of the form 2^n-k and beyond, arXiv:2307.07894 [math.NT], 2023.

Crossrefs

Cf. A057912 (3*2^k - 5 is prime).

Programs

Mathematica

Do[ If[ PrimeQ[ 3*2^n + 5 ], Print[ n ] ], {n, 1, 3000} ]

PARI

{for(n=0, 10^6, if(isprime(k=5+3*2^n), print1(n, ", ")))} /* Joerg Arndt, Apr 13 2012 */

Extensions

a(54) from Jinyuan Wang, Feb 02 2020