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 A027115 #4 Mar 30 2012 18:56:14 %S A027115 1,4,11,31,87,246,700,2003,5758,16616,48102,139625,406214,1184138, %T A027115 3457771,10112245,29613029,86824136,254840534,748725393,2201731878, %U A027115 6479790418,19084605389,56247812793,165884498711,489512360356 %N A027115 a(n) = T(n,0) + T(n,1) + ... + T(n,2n), T given by A027113. %K A027115 nonn %O A027115 0,2 %A A027115 _Clark Kimberling_