A016108 Numbers k=3*m+1 such that 2^m == 1 (mod k).

1, 31, 43, 109, 127, 157, 223, 229, 277, 283, 307, 397, 433, 439, 457, 499, 601, 643, 691, 727, 733, 739, 811, 919, 997, 1021, 1051, 1069, 1093, 1327, 1399, 1423, 1459, 1471, 1579, 1597, 1627, 1657, 1699, 1723, 1729, 1753, 1777, 1789, 1801, 1831, 1933, 1999, 2017, 2047, 2089, 2113, 2143, 2179, 2203

Offset: 1

Author

Max Alekseyev, Jun 23 2012

Keywords

• nonn

Comments

Prime terms are listed in A014752.

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A014752.

Programs

Mathematica

Join[{1},Select[Table[3m+1,{m,1000}],PowerMod[2,(#-1)/3,#]==1&]] (* Harvey P. Dale, Apr 26 2016 *)