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 A049731 #4 Mar 30 2012 18:56:56 %S A049731 18,33,54,79,115,152,197,253,310,370,443,516,600,697,789,894,995,1115, %T A049731 1232,1360,1497,1626,1786,1931,2091,2252,2421,2609,2786,2982,3171, %U A049731 3367,3584,3797,4029,4254,4478,4723,4960,5232,5481 %N A049731 a(n)=T(n,n+3), array T as in A049723. %K A049731 nonn %O A049731 0,1 %A A049731 _Clark Kimberling_