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 A047103 #4 Mar 30 2012 18:56:53 %S A047103 1,1,5,16,58,220,821,3090,11743,44792,171495,659051,2540116,9814642, %T A047103 38007320,147472450,573200298,2231386904,8698569320,33952074197, %U A047103 132672190652,518973027214,2031995088017,7963057824045,31231061046115 %N A047103 T(n,n-1), array T as in A047100. %K A047103 nonn %O A047103 1,3 %A A047103 _Clark Kimberling_