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 A072840 #21 Jul 01 2021 15:37:44 %S A072840 1,0,0,0,0,0,0,0,0,20,0,0,0,0,0,0,90,0,0,0,90,240,0,0,420,252,0,0,0, %T A072840 720,0,0,0,0,0,0,1700,0,0,0,1260,2700,0,0,3240,1680,0,0,0,5220,0,0,0, %U A072840 0,0,0,7740,0,0,0,4920,10080,0,0,12690,7020,0,0,0,15120,0,0,0,0,0,0,22680,0,0 %N A072840 Duplicate of A023921. %K A072840 dead %O A072840 0,10