A192109 Numbers k that divide 2^(k-1) - 2.

1, 2, 6, 10, 14, 22, 26, 30, 34, 38, 46, 58, 62, 74, 82, 86, 94, 106, 118, 122, 134, 142, 146, 158, 166, 170, 178, 182, 194, 202, 206, 214, 218, 226, 254, 262, 274, 278, 298, 302, 314, 326, 334, 346, 358, 362, 382, 386, 394, 398, 422, 446, 454, 458, 466, 478, 482, 502, 514, 526, 538, 542, 554, 562, 566, 586, 614, 622, 626

Offset

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Reinhard Zumkeller)

Mathematica

Join[{1, 2}, Select[Range[700], PowerMod[2, #-1, #]==2&]] (* Harvey P. Dale, May 15 2015 *)

Prog

(Haskell)
import Data.List (elemIndices)
a192109 n = a192109_list !! (n-1)
a192109_list = map (+ 1) $ elemIndices 0 $ zipWith mod a000918_list [1..]
-- Reinhard Zumkeller, Apr 23 2013
(PARI) is(n)=Mod(2, n)^(n-1)==2 \\ Charles R Greathouse IV, Nov 04 2016

Crossrefs

Contains A216090 as subsequence.

Subsequence of A015921, consisting of the terms that are not multiples of 4.

The odd terms form A173572.

Cf. A014741, A000918.

Sequence in context: A239221 A039956 A197930 * A216090 A378458 A342641

Adjacent sequences: A192106 A192107 A192108 * A192110 A192111 A192112

Keyword

nonn

Author

Max Alekseyev, Apr 22 2013

Status

approved