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 A141471 #3 Mar 30 2012 18:51:58 %S A141471 1,0,1,2,1,1,1,4,7,2,10,7,5,4,1,5,1,14,10,8,19,1,19,8,13,17,23,10,13, %T A141471 35,11,28,16,31,37,19,32,31,29,14,13,31,40,1,4,37,50,11,5,55,53,50,47, %U A141471 17,49,47,35,49,16,22,16,44,73,5,38,76,31,23,83,25,53,50,61,1 %N A141471 Number of 2's in A139067(n). %Y A141471 Cf. A139067. %K A141471 nonn,base %O A141471 1,4 %A A141471 _Paul Curtz_ and _Ray Chandler_, Aug 14 2008