A016108 - OEIS

%I #15 May 26 2024 01:03:13

%S 1,31,43,109,127,157,223,229,277,283,307,397,433,439,457,499,601,643,

%T 691,727,733,739,811,919,997,1021,1051,1069,1093,1327,1399,1423,1459,

%U 1471,1579,1597,1627,1657,1699,1723,1729,1753,1777,1789,1801,1831,1933,1999,2017,2047,2089,2113,2143,2179,2203

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

%C Prime terms are listed in A014752.

%H Harvey P. Dale, <a href="/A016108/b016108.txt">Table of n, a(n) for n = 1..1000</a>

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

%Y Cf. A014752.

%K nonn

%O 1,2

%A _Max Alekseyev_, Jun 23 2012