This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A070682 #7 Dec 05 2013 19:55:19
%S A070682 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 A070682 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 A070682 112,0,6,48,22,5,0,42,21,130,18,0,8,46,46,6,0,42,148
%N A070682 Smallest m in range 1..phi(2n+1) such that 10^m == 1 mod 2n+1, or 0 if no such number exists.
%o A070682 (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 A070682 Cf. A070667-A070675, A002326, A070676, A053447, A070677, A070678, A053451, A070679, A070681, A070680, A070683.
%K A070682 nonn
%O A070682 0,4
%A A070682 _N. J. A. Sloane_ and _Amarnath Murthy_, May 08 2002