%I

%S 1,3,0,6,3,2,6,0,109,103,6,100001,0,9,1006,17,6,0,3,6,5,103,0,1000002,

%T 6,129,100012,0

%N Smallest k such that the concatenation from 1 to k and back to 1 is divisible by 2n-1, or 0 if no such k exists.

%C a(29), 2n-1 = 57, is at least 1e8.

%Y Cf. A077189.

%K base,nonn

%O 1,2

%A _Franklin T. Adams-Watters_, Jun 02 2006