A216848 - OEIS

%I #23 Jan 12 2024 01:15:23

%S 7,15,17,21,23,31,33,35,39,41,43,45,47,49,51,55,57,63,65,69,71,73,75,

%T 77,79,85,87,89,91,93,95,97,99,103,105,109,111,113,115,117,119,123,

%U 127,129,133,135,137,141,143,145,147,151,153,155,157,159,161,165,167

%N Odd numbers for which 2 is not a primitive root.

%H Amiram Eldar, <a href="/A216848/b216848.txt">Table of n, a(n) for n = 1..10000</a>

%t nn = 200; Select[Range[3, nn, 2], PrimitiveRoot[#] =!= 2 &] (* _T. D. Noe_, Sep 19 2012 *)

%o (PARI) forstep(p=3, 200, 2, if(znorder(Mod(2, p))!=eulerphi(p), print(p)))

%Y Cf. A002326, A001122, A216838.

%K nonn

%O 1,1

%A _V. Raman_, Sep 17 2012