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 A171902 #6 Sep 14 2013 13:41:23 %S A171902 11,11,11,11,11,11,11,11,1,10,1,1,1,1,1,1,1,1,1,3,11,11,11,11,11,11, %T A171902 11,1,11,9,1,1,1,1,1,1,1,1,1,4,11,11,11,11,11,11,1,11,11,8,1,1,1,1,1, %U A171902 1,1,1,1,5,11,11,11,11,11,1,11,11,11,7,1,1,1,1,1,1,1,1,1,6,11,11,11,11,1,11 %N A171902 First differences of consecutive numbers having at least two identical neighboring digits in decimal representation. %C A171902 a(n) = A171901(n+1) - A171901(n); %C A171902 1 <= a(n) <= 11; %C A171902 a(A171903(n)) = 1. %H A171902 R. Zumkeller, <a href="/A171902/b171902.txt">Table of n, a(n) for n = 1..10000</a> %K A171902 nonn,base %O A171902 1,1 %A A171902 _Reinhard Zumkeller_, Feb 07 2010