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 A014895 #5 Mar 30 2012 17:28:13 %S A014895 2787,2788,2793,2794,2940,3125,5912,5913,5918,5919,6065,6250,9037, %T A014895 9038,9043,9044,9190 %N A014895 n is equal to the number of 3s in all numbers <= n written in base 5. %Y A014895 Cf. A014778. %K A014895 nonn,base,fini,full %O A014895 1,1 %A A014895 _Olivier Gérard_ %E A014895 List proved complete by _Hugo van der Sanden_ (cf. A014886).