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 A127851 #2 Mar 30 2012 18:59:19 %S A127851 0,1,11,1110,1111000,11111000000,1111110000000000, %T A127851 1111111000000000000000,11111111000000000000000000000, %U A127851 1111111110000000000000000000000000000 %N A127851 a(n) has n 1's followed by C(n-1,2) 0's. %C A127851 Base 2 version of A127850. %F A127851 a(n)=10^C(n,2)*(10^n-1)/(9*10^(n-1)) %K A127851 easy,nonn %O A127851 0,3 %A A127851 _Paul Barry_, Feb 02 2007