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 A140080 #6 May 05 2014 15:02:12 %S A140080 0,1,1,0,1,2,0,1,1,0,2,1,0,1,1,0,1,2,0,1,2,0,1,1,0,1,1,0,1,1,0,1,1,0, %T A140080 2,1,0,1,1,0,2,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,2,0,1, %U A140080 2,0,1,1,0,1,1,0,1,1,0,1,2,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1 %N A140080 Fix e = 3; a(n) = minimal Hamming distance between the binary representation of n and the binary representation of any multiple ke (0 <= k <= n/e) which is a child of n. %C A140080 A number m is a child of n if the binary representation of n has a 1 in every position where the binary representation of m has a 1. %C A140080 In other words, this tells us how closely (in Hamming weight) we can approximate n "from below" by a multiple of e. %H A140080 Nadia Heninger and N. J. A. Sloane, <a href="/A140080/b140080.txt">Table of n, a(n) for n = 0..5000</a> %H A140080 N. J. A. Sloane, <a href="/A140080/a140080.f.txt">Fortran program for this and related sequences</a> %e A140080 If n = 14 = 1110_2, take k=2, ke = 6 = 110_2, which is Hamming distance 1 from n. This is the best we can do, so a(14) = 1. %o A140080 (Fortran) See Sloane link. %Y A140080 For e=2 and 4 through 9 see A000035 and A140081 through A140086. %Y A140080 Cf. A140137, A140138, A140200-A140206. %K A140080 nonn %O A140080 0,6 %A A140080 _Nadia Heninger_ and _N. J. A. Sloane_, Jun 03 2008