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%I #7 Dec 05 2013 19:55:19
%S 0,1,0,6,1,2,6,0,16,18,6,22,0,3,28,15,2,0,3,6,5,21,0,46,42,16,13,0,18,
%T 58,60,6,0,33,22,35,8,0,6,13,9,41,0,28,44,6,15,0,96,2,4,34,0,53,108,3,
%U 112,0,6,48,22,5,0,42,21,130,18,0,8,46,46,6,0,42,148
%N Smallest m in range 1..phi(2n+1) such that 10^m == 1 mod 2n+1, or 0 if no such number exists.
%o (PARI) a(n) = {for (m = 1, eulerphi(2*n+1), if (10^m % (2*n+1) == 1, return (m));); return (0);} \\ _Michel Marcus_, Sep 14 2013
%Y Cf. A070667-A070675, A002326, A070676, A053447, A070677, A070678, A053451, A070679, A070681, A070680, A070683.
%K nonn
%O 0,4
%A _N. J. A. Sloane_ and _Amarnath Murthy_, May 08 2002
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