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 A047125 #4 Mar 30 2012 18:56:53 %S A047125 1,2,6,28,120,501,2020,8062,31992,126556,499478,1968504,7751812, %T A047125 30513489,120090702,472636988,1860354732,7323975621,28840527086, %U A047125 113600162826,447592682400,1764087889221,6954932056860,27428450072466 %N A047125 T(n,n-3), array T as in A047120. %K A047125 nonn %O A047125 3,2 %A A047125 _Clark Kimberling_