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 A054139 #4 Mar 30 2012 18:57:03 %S A054139 1,4,18,97,570,3489,21810,138044,881098,5658793,36520068,236619717, %T A054139 1538134272,10026366588,65513185896,428957025672 %N A054139 T(2n,n), array T as in A054134. %K A054139 nonn %O A054139 0,2 %A A054139 _Clark Kimberling_