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 A212720 #12 Mar 07 2017 10:01:18
%S A212720 0,6,0,0,3,857142,0,8,0,90,6,923076,285714,3,0,9411764705882352,4,
%T A212720 947368421052631578,0,952380,54,9565217391304347826086,3,0,615384,962,
%U A212720 428571,9655172413793103448275862068,6,967741935483870,0,96,7058823529411764,714285,2,972
%N A212720 The periodic part of the decimal expansion of n/(n+1). Any initial 0's are to be placed at end of cycle.
%H A212720 Jaroslav Krizek, <a href="/A212720/b212720.txt">Table of n, a(n) for n = 1..100</a>
%e A212720 6/7 = 0.85714285714285714285714285714286... and digit-cycle is 857142, so a(6) = 857142.
%t A212720 Table[FromDigits[FindTransientRepeat[RealDigits[n/(n+1),10,100][[1]],3][[2]]],{n,40}] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Mar 07 2017 *)
%Y A212720 Cf. A036275 (periodic part of the decimal expansion of 1/n), A158911 (numbers n such that a(n)=0), A051037.
%K A212720 nonn,base
%O A212720 1,2
%A A212720 _Jaroslav Krizek_, Jun 01 2012