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 A047123 #4 Mar 30 2012 18:56:53 %S A047123 1,1,4,16,58,215,806,3051,11602,44307,169840,653204,2519314,9740350, %T A047123 37739300,146498531,569642584,2218322463,8650367796,33773500347, %U A047123 132008143328,516495270723,2022721237326,7928249018667,31100068617294 %N A047123 T(n,n-1), array T as in A047120. %K A047123 nonn %O A047123 1,3 %A A047123 _Clark Kimberling_