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 A074136 #3 Dec 05 2013 19:55:33 %S A074136 1,4,7,13,18,21,28,40,49,64,75,81,94,115,130,138,155,182,201,211,232, %T A074136 265,288,300,325,364,391,433,462,477,508,556,589,606,641,695,732,751, %U A074136 790,850,891,912,955,1021,1066,1089,1136,1208,1257,1282,1333,1411,1464 %N A074136 Main diagonal of triangle A074135. %Y A074136 Cf. A074135. %K A074136 nonn,easy,less %O A074136 1,2 %A A074136 _Amarnath Murthy_, Aug 27 2002