A180924 Numbers k such that 12321*2^k + 1 is prime.

4, 24, 29, 47, 61, 63, 67, 69, 87, 101, 129, 143, 153, 249, 252, 333, 408, 561, 616, 732, 929, 1349, 3467, 6156, 6919, 9244, 14413, 17128, 20059, 20169, 20512, 23479, 24076, 26208, 27189, 34113, 37648, 43893, 45537, 63107, 79527, 88752

Offset

1,1

Comments

a(43) > 10^5. - Michael S. Branicky, Jan 13 2026

Links

Table of n, a(n) for n=1..42.

Prog

(PARI) is(n)=ispseudoprime(12321<<n+1) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Cf. A080076.

Sequence in context: A348299 A144137 A238222 * A366190 A176900 A166727

Adjacent sequences: A180921 A180922 A180923 * A180925 A180926 A180927

Keyword

nonn,hard,more

Author

Jason Earls, Sep 25 2010

Extensions

a(36)-a(42) from Michael S. Branicky, Jan 13 2026

Status

approved