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 A047117 #4 Mar 30 2012 18:56:53 %S A047117 1,3,9,33,115,401,1482,5449,20048,75303,283599,1069860,4070772, %T A047117 15539326,59433763,228278533,879053987,3391075968,13113667186, %U A047117 50808921375,197150760045,766241841810,2982295208876,11621280655944 %N A047117 T(n,n+2), array T as in A047110. %K A047117 nonn %O A047117 0,2 %A A047117 _Clark Kimberling_