The nth Mobius number is given by the piecewise function:
/ 0 if n has any repeated factors
|
/
u(n) = | 1 if n=1
\
| k
\ (-1) if n is a product of k distinct primes
The first several values of u(n) (n=1,2,3,...) are u(n)=1, -1, -1, 0, -1, 1, ... Mobius numbers are multiplicative, i.e.:
/ u(m)*u(n) if gcd(m,n)=1
u(m*n) = |
\ 0 otherwise
All information gathered from http://mathworld.wolfram.com/MoebiusFunction.html