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 A047126 #4 Mar 30 2012 18:56:53 %S A047126 1,2,6,20,71,256,938,3480,13041,49234,186968,713428,2733218,10506788, %T A047126 40506442,156554820,606400307,2353368138,9148789134,35620615548, %U A047126 138878821241,542138013480,2118718654794,8288638523100,32456517032946 %N A047126 T(n,n+1), array T as in A047120. %K A047126 nonn %O A047126 0,2 %A A047126 _Clark Kimberling_