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 A047142 #4 Mar 30 2012 18:56:53 %S A047142 1,2,4,10,38,142,470,1576,5940,22714,83456,305088,1158606,4456076, %T A047142 16946498,64189932,246350606,952607962,3675557676,14158562010, %U A047142 54805236890,213011072542,828185178452,3219077811678,12537974366478 %N A047142 T(n,n), array T as in A047140. %K A047142 nonn %O A047142 0,2 %A A047142 _Clark Kimberling_