Liouville's function denoted
is defined as follows:
![]()
Liouville's function is completely multiplicative since if
and
then
![]()
Theorem
For
we have
![]()
Also
for all![]()
Proof: Let
then
is multiplicative so to determine
we only need to compute
for all
We have
![]()
![]()
Hence if
we have
If any exponent
is odd then
so
If all the exponents are even then
for all
and
This shows that
is a square and
otherwise. Also![]()