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 A139069 #4 Mar 30 2012 18:51:57 %S A139069 0,1,1,1,2,3,3,4,3,3,3,2,4,4,4,5,5,5,3,3,3,3,5,5,2,3,5,5,6,5,6,1,3,3, %T A139069 3,3,3,4,3,3,4,7,3,7,5,5,5,4,5,7,2,5,4,4,5,5,4,5,4,5,2,4,4,4,4,5,5,4, %U A139069 4,5,5,7,7,4,5,7,7,5,7,7,8,7,7,3,3,5,5,3,6,3,6,6,3,5,5,5,3,6,6 %N A139069 Number of 3's in A020458(n). %K A139069 nonn,base %O A139069 1,5 %A A139069 _Paul Curtz_, Jun 05 2008 %E A139069 More terms from _Ray Chandler_, Aug 06 2008