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 A215089 #7 Aug 03 2012 15:08:50
%S A215089 0,1,2,3,4,5,2,3,4,5,6,7,4,5,6,7,8,9,6,7,8,9,10,11,8,9,10,11,12,13,10,
%T A215089 11,12,13,14,15,4,5,6,7,8,9,6,7,8,9,10,11,8,9,10,11,12,13,10,11,12,13,
%U A215089 14,15,12,13,14,15,16,17,14,15,16,17,18,19,8,9,10,11,12,13,10
%N A215089 a(n)=Sum{d(i)*6^i: i=0,1,...,m}, where Sum{d(i)*2^i: i=0,1,...,m} is the base 2 representation of n.
%H A215089 Clark Kimberling, <a href="/A215089/b215089.txt">Table of n, a(n) for n = 0..1000</a>
%F A215089 a(n) = 2*a(n/6) if n = 0 mod 6; otherwise a(n) = a(n-1)+1.
%t A215089 t = Table[FromDigits[RealDigits[n, 6], 2], {n, 0, 100}]
%Y A215089 Cf. A033043.
%K A215089 nonn,easy
%O A215089 0,3
%A A215089 _Clark Kimberling_, Aug 03 2012