A322952 Numbers k such that 321*2^k+1 is prime.

1, 5, 32, 68, 109, 128, 133, 212, 241, 653, 776, 1339, 1787, 2659, 6388, 6547, 8365, 16699, 62861, 64795, 83227, 195376, 278875, 442480, 542876, 730321, 1168576, 1257859, 1629307, 4715725

Offset

1,2

Links

Table of n, a(n) for n=1..30.

Ray Ballinger, Proth Search Page

Ray Ballinger and Wilfrid Keller, List of primes k.2^n + 1 for 300 < k < 600

Y. Gallot, Proth.exe: Windows Program for Finding Large Primes

Wilfrid Keller, List of primes k.2^n - 1 for k < 300

Eric Weisstein's World of Mathematics, Proth Prime

Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime

Maple

select(n->isprime(321*2^n+1), [$1..1000]); # Muniru A Asiru, Dec 31 2018

Mathematica

Select[Range[1000], PrimeQ[321*2^# + 1] &] (* Robert Price, Dec 31 2018 *)

Crossrefs

Cf. A002255, A050527.

Sequence in context: A140154 A350997 A073694 * A101966 A341423 A184536

Adjacent sequences: A322949 A322950 A322951 * A322953 A322954 A322955

Keyword

nonn,more,hard

Author

Robert Price, Dec 31 2018

Extensions

a(30) from Jeppe Stig Nielsen, Dec 20 2024

Status

approved