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 A055139 #3 Mar 30 2012 17:37:10 %S A055139 1,-1,0,1,-1,-1,4,-1,-19,31,120,-483,-933,8623,6748,-189589,41561, %T A055139 5147391,-6328400,-170622599,394612599,6807529823,-23890335372, %U A055139 -322371010985,1564733285829,17884889743135,-114158790326872 %N A055139 Column 0 of triangle A055138. %K A055139 sign %O A055139 0,7 %A A055139 _Christian G. Bower_, May 09 2000