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 A152739 #4 Mar 30 2012 18:51:59 %S A152739 1,2,3,4,5,4,6,5,4,7,8,7,6,5,9,8,7,6,10,8,11,10,9,8,7,12,11,9,8,13,11 %N A152739 Sqrt((even members of A118962)/2). %C A152739 Contains one 1, one 2, one 3, three 4's, .... %Y A152739 A137912. %K A152739 nonn %O A152739 1,2 %A A152739 _Paul Curtz_, Dec 12 2008 %E A152739 Edited by _N. J. A. Sloane_, Dec 13 2008