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 A091615 #3 Mar 30 2012 17:37:13 %S A091615 1,2,1,6,0,1,11,6,0,1,26,12,4,0,1,61,26,10,4,0,1,132,70,26,8,4,0,1, %T A091615 290,174,62,24,8,4,0,1,638,404,156,60,22,8,4,0,1,1390,946,385,146,58, %U A091615 22,8,4,0,1,3012,2192,921,362,144,56,22,8,4,0,1,6496,5008,2177,876,350,142 %N A091615 Matrix square of triangle A091613. %e A091615 1; 2,1; 6,0,1; 11,6,0,1; 26,12,4,0,1; ... %Y A091615 Row sums: A091621. Column 1: A091622. %K A091615 nonn,tabl %O A091615 1,2 %A A091615 _Christian G. Bower_, Jan 23 2004