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 A161137 #2 Mar 30 2012 17:27:02 %S A161137 1,2,5,9,37,86,232,748,932,2865,17761,109780,249840,1190787,3869645, %T A161137 6479631,69445201,75334942 %N A161137 Main diagonal of the triangular array A161135. %F A161137 a(m) = A161135(m,m) %Y A161137 A161135, A161136, A161138 %K A161137 more,nonn %O A161137 1,2 %A A161137 _Max Alekseyev_, Jun 02 2009