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 A118021 #2 Mar 30 2012 17:22:42 %S A118021 2,4,8,16,20,40,64,72,80,100,120,128,136,240,300,376,404,432 %N A118021 Numbers n such that (1+n)/n does not converge to an integer under the approximate cubing map x -> x*ceiling(x^2). %F A118021 A118020(n)=-1. %K A118021 nonn %O A118021 1,1 %A A118021 _T. D. Noe_, Apr 10 2006