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 A158859 #3 Mar 30 2012 18:52:03 %S A158859 1,333,55555,7777777,999999999,11111111111,3333333333333, %T A158859 555555555555555,77777777777777777,9999999999999999999, %U A158859 111111111111111111111,33333333333333333333333 %N A158859 a(n) is formed by 2n+1 concatenations of the digit 2r+1 where n=r (mod 5). %C A158859 One 1, three 3's, five 5's, seven 7's, nine 9's, eleven 1's, thirteen 3's, %Y A158859 Cf. A158849. %K A158859 nonn,base %O A158859 0,2 %A A158859 _Paul Curtz_, Mar 28 2009 %E A158859 Definition modified by _R. J. Mathar_, Apr 06 2009