%I #10 Jul 24 2021 05:41:03
%S 10,15,21,30,35,38,42,45,46,58,60,62,70,74,82,84,86,90,94,105,106,118,
%T 122,126,132,134,140,142,146,158,166,178,180,182,185,190,194,202,206,
%U 210,214,215,217,218,219,222,226,228,231,237,249,252,254,258,259,262
%N Composite numbers k such that 6^k (mod k) is a power of 6 greater than 1.
%H Amiram Eldar, <a href="/A129496/b129496.txt">Table of n, a(n) for n = 1..10000</a>
%e 38 is a member of the sequence since 6^38 (mod 38) == 36.
%t Select[Range@ 266, (p = PowerMod[6, #, #]) > 1 && IntegerQ@ Log[6, p] && CompositeQ[#] &] (* corrected by _Amiram Eldar_, Jul 24 2021 *)
%Y Cf. A036236, A129492, A129493, A129494, A129495, A129497.
%K easy,nonn
%O 1,1
%A _Robert G. Wilson v_, Apr 17 2007