A112984 Numbers k such that 2^k mod k-1 is odd.

4, 10, 16, 28, 36, 50, 56, 76, 82, 106, 116, 120, 122, 134, 144, 162, 172, 176, 188, 190, 204, 216, 218, 232, 236, 244, 248, 254, 256, 262, 274, 280, 290, 296, 298, 300, 324, 334, 336, 344, 352, 364, 372, 396, 404, 406, 414, 426, 438, 452, 456, 474, 476, 484

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Mathematica

Select[ 2Range[250], OddQ[ PowerMod[2, #, #-1]] &] (* Robert G. Wilson v, Oct 10 2005 *)

Prog

(PARI) isok(k) = if( k < 2, 0, lift((Mod(2, k-1)^k)) % 2); \\ Amiram Eldar, Feb 01 2026

Crossrefs

Cf. A112983, A015911.

Sequence in context: A175703 A132227 A036063 * A343907 A191115 A073121

Adjacent sequences: A112981 A112982 A112983 * A112985 A112986 A112987

Keyword

nonn

Author

Paul Barry, Oct 08 2005

Extensions

More terms from Robert G. Wilson v, Oct 10 2005

Status

approved