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 A009012 #6 Mar 30 2012 18:35:07 %S A009012 4,8,12,12,15,16,20,21,24,24,24,28,30,32,35,36,36,40,40,42,44,45,45, %T A009012 48,48,48,52,55,56,56,60,60,60,60,63,63,64,68,70,72,72,72,72,75,76,77, %U A009012 80,80,80,84,84,84,84,88,90,90,91,92,96,96,96,99,100,104,105,105,105,105,108 %N A009012 Ordered long legs of Pythagorean triangles. %Y A009012 Very similar to A046084!. %K A009012 nonn %O A009012 1,1 %A A009012 _David W. Wilson_