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 A129972 #28 Jan 17 2017 13:06:22
%S A129972 1,3,3,5,5,5,5,7,7,7,7,7,7,7,7,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,11,11,
%T A129972 11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
%U A129972 11,11,11,11,11,11,11,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13,13
%N A129972 a(n) = 2*floor(log_2(n)) + 1.
%C A129972 The number of bits needed to write n using Elias gamma coding. - _Charles R Greathouse IV_, Mar 21 2012
%C A129972 Consists of the n-th odd number (A005408(n) = 2n+1) repeated 2^(n-1) times (since a(n) = a(n-1) except when a(n) > a(n-1) which happens for n a power of 2). - _Jonathan Vos Post_, Jun 17 2007
%H A129972 Indranil Ghosh, <a href="/A129972/b129972.txt">Table of n, a(n) for n = 1..10000</a>
%F A129972 a(n) = Sum_{k=1..n} (-1)^(k-1)*floor(n/k)*mu(k).
%o A129972 (PARI) a(n)=2*floor(log(n)/log(2))+1
%o A129972 (PARI) a(n)=log(n+.5)\log(2)*2+1 \\ _Charles R Greathouse IV_, Mar 21 2012
%o A129972 (PARI) a(n)=2*logint(n,2)+1 \\ _Charles R Greathouse IV_, Sep 04 2015
%Y A129972 Cf. A005408.
%Y A129972 Cf. A281149 (See the comment section by _Charles R Greathouse IV_, of this sequence (A129972) ). - _Indranil Ghosh_, Jan 17 2017
%K A129972 nonn,easy
%O A129972 1,2
%A A129972 _Benoit Cloitre_, Jun 13 2007