Sum{k|m, k<= sqrt(m)} mu(k)
Leroy Quet
qq-quet at mindspring.com
Wed Nov 5 02:25:01 CET 2003
[I just posted this set of questions to sci.math, but I do not expect
many responses there.]
If mu(k) is the Mobius(Moebius) function,
then
sum{k|m, k<= sqrt(m)} mu(k)
gives us the sequence:
1, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, -1, 1, 0, 0, 0,...
(Sequence A068101 in the EIS:
http://www.research.att.com/projects/OEIS?Anum=A068101 )
What can be said about this sequence, such as its asymptotics,
the expected number of 0's, +-1's, +-2's, etc below any given value,
and (perhaps) even what its closed-form might be??
All I can deduce right now is that, unspectacularly,
sum{m=1 to n} sum{k|m, k<= sqrt(m)} mu(k) =
sum{1<=k<=sqrt(n)} mu(k) (floor(n/k) +1 -k).
Thanks,
Leroy Quet
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