%I #2 Mar 30 2012 18:39:28
%S 0,1,0,1,0,1,2,3,2,3,4,3,4,3,4,5,4,5,4,5,6,7,6,7,8,9,8,9,8,9,10,9,10,
%T 11,12,11,12,13,12,13,12,13,14,15,14,15,16,17,16,17,18,17,18,17,18,19,
%U 18,19,18,19,20,21,20,21,22,21,22,21,22,23,22,23,24,25,24,25,26,27,26,27
%N a(n)=A156253(n)-A156251(n)
%C a(2n) is odd, a(2n+1) is even.
%F a(n) is expected to be asymptotic to n/3.
%K nonn
%O 1,7
%A _Benoit Cloitre_, Feb 14 2009