%I A036538
%S A036538 2,3,7,12,23,45,89,178,356,707,1409,2822,5639,11273,22546,45088,90165,
%T A036538 180315,360637
%N A036538 Number of integers m below 2^n such that d(m) = 2^k for some k=0,1,2,
               3..
%C A036538 a[ n+1 ]/a[ n ] is very close to 2; a[ n ]/2^n is near to 0.7
%F A036538 bi[ x_ ] := 1-Sign[ N[ Log[ 2, x ], 5 ]-Floor[ N[ Log[ 2, x ], 5 ] ] 
               ], ld[ x_ ] := Length[ Divisors[ x ] ], Table[ Length[ Flatten[ Position[ 
               Table[ bi[ ld[ x ] ], {x, 1, 2^m} ], 1 ] ] ], {m, 1, 19} ]
%e A036538 From numbers not exceeding 16=2^4, only 4,9,12 and 16 are not in the 
               sequence, so a[ 4 ]=16-4=12
%Y A036538 Cf. A000005, A036537, A036539, A037992.
%Y A036538 Sequence in context: A027675 A054176 A000630 this_sequence A108742 A018240 
               A090596
%Y A036538 Adjacent sequences: A036535 A036536 A036537 this_sequence A036539 A036540 
               A036541
%K A036538 nonn
%O A036538 1,1
%A A036538 Labos E. (labos(AT)ana.sote.hu)