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 A047004 #4 Mar 30 2012 18:56:51 %S A047004 1,1,4,7,30,143,585,2420,9690,38779,153769,608925,2404100,9484317, %T A047004 37378622,147270615,580094570,2284987355,9001081353,35463025663, %U A047004 139747015800,550824207900,2171675252565,8564359325319,33784352403732 %N A047004 T(n,n-2), array T given by A047000. %K A047004 nonn %O A047004 2,3 %A A047004 _Clark Kimberling_