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 A109264 #2 Mar 30 2012 18:59:08 %S A109264 1,-1,1,-1,-2,1,0,0,-3,1,0,1,2,-4,1,0,0,1,5,-5,1,0,0,-1,-1,9,-6,1,0,0, %T A109264 0,-2,-6,14,-7,1,0,0,0,1,-1,-15,20,-8,1,0,0,0,0,3,5,-29,27,-9,1,0,0,0, %U A109264 0,-1,4,20,-49,35,-10,1,0,0,0,0,0,-4,-1,49,-76,44,-11,1,0,0,0,0,0,1,-8,-21,98,-111,54,-12,1 %N A109264 Riordan array (1-x-x^2,x(1-x)). %C A109264 Rows sums are A109265. Diagonal sums are A109266. Inverse is A109267. %e A109264 Rows begin %e A109264 1; %e A109264 -1,1; %e A109264 -1,-2,1; %e A109264 0,0,-3,1; %e A109264 0,1,2,-4,1; %e A109264 0,0,1,5,-5,1; %e A109264 0,0,-1,-1,9,-6,1; %K A109264 easy,sign,tabl %O A109264 0,5 %A A109264 _Paul Barry_, Jun 24 2005