A173022 - OEIS

%I #3 Mar 30 2012 18:51:05

%S 1,1,1,2,2,2,3,4,4,4,4,4,5,5,6,7,7,7,7,7,7,7,7,7,8,8,8,9,10,10,11,12,

%T 12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,13,13,13,14,14,14,15,

%U 16,17,17,17,18,19,19,20,21,21,21,21,21,21,21,21,21,21,21,21,21,21,21,21

%N Number of numbers <= n having no isolated ones in their binary representations.

%C a(A144795(n+1)) = a(A144795(n)) + 1;

%C a(2^n - 1)) = A005251(n+1);

%C A173021(n) <= a(n) <= A173023(n).

%H R. Zumkeller, <a href="/A173022/b173022.txt">Table of n, a(n) for n = 0..10000</a>

%e a(20)=#{0,3,6,7,12,14,15}=#{0,11,110,111,1100,1110,1111}=7.

%K base,nonn

%O 0,4

%A _Reinhard Zumkeller_, Feb 07 2010