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 A072860 #6 Mar 30 2012 18:39:04 %S A072860 0,1,0,3,1,3,1,9,1,1,3,3,1,3,1,1,1,3,3,1,1,1,1,1,3,1,1,1,27,1,3,1,1,1, %T A072860 1,3,3,81,1,1,1,9,1,3,1,9,3,3,1,3,1,1,3,1,1,1,1,1,3,1,3,1,9,1,3,1,1,3, %U A072860 1,1,1,1,3,3,27,1,1,9,1,3,1,1,1,27,3,1,1,1,1,1,1,1,243,1,3,1,1,1,9,27 %N A072860 Highest power of 3 dividing the period length of 1/prime(n) = A002371(n). %o A072860 (PARI) for n>3 ? a(n)=if(n<4,n==2,znorder(Mod(10, prime(n)))) ? for(n=4,150,print1(gcd(a(n),3^100),",")) %Y A072860 Cf. A002371. %K A072860 base,easy,nonn %O A072860 1,4 %A A072860 _Benoit Cloitre_, Jul 26 2002