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%I #31 May 19 2018 02:35:39
%S 1,1,0,1,2,2,4,8,13,22,39,77,137,254,459,889,1665,3175,6041,11619,
%T 22319,42979,83123,160649,311826,605225,1176998,2291702,4466923,
%U 8716126,17023771,33279942,65109458,127484313,249783733,489738130,960801221,1886039740
%N Number of refactorable integers (A033950) of binary order (A029837) n.
%C Since for any epsilon d(n) <= n^epsilon if n is large enough, a(n) does not grow very quickly.
%e {1} has binary order 0, {2} has binary order 1, no term has binary order 2, {8} has binary order 3, {9,12} have binary order 4, {18,24} have binary order 5, ...
%e The 8 numbers, between 65 and 128 (with binary order 7) which are divided by d(x) (A000005) are 72,80,84,88,96,104,108,128, so a(7)=8.
%p with(numtheory): A036761 := proc(n) local ct,k,lim: if(n=0)then return 1: else ct:=0: lim:=2^n: for k from 2^(n-1)+1 to lim do if(k mod tau(k) = 0)then ct:=ct+1: fi: od: return ct: fi: end: seq(A036761(n),n=0..10); # _Nathaniel Johnston_, May 04 2011
%t Table[Count[Range[2^(n - 1) + 1, 2^(n)], k_ /; Divisible[k, DivisorSigma[0, k]]] + Boole[n == 0], {n, 0, 22}] (* _Michael De Vlieger_, May 20 2017 *)
%Y Cf. A000005, A029837, A033950.
%K nonn
%O 0,5
%A _Labos Elemer_
%E a(22)-a(37) from _Donovan Johnson_, Aug 29 2012