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 A049720 #4 Mar 30 2012 18:56:56 %S A049720 3,4,8,13,19,28,37,48,62,75,92,108,127,150,170,195,218,247,277,304, %T A049720 337,369,406,441,475,518,559,604,646,689,740,786,841,890,945,1001, %U A049720 1052,1115,1173,1236,1299,1360,1428,1497,1568,1638,1707 %N A049720 a(n)=T(n,1), array T as in A048149. %K A049720 nonn %O A049720 0,1 %A A049720 _Clark Kimberling_