Science:Math Exam Resources/Courses/MATH312/December 2009/Question 05 (a)/Hint 1

Recall that the Mobius function is the function that evaluates to 1 if n is square-free and has an even number of prime factors, -1 if n is square-free and has an odd number of factors, and 0 if n has a square factor.

First show/recall that the Mobius function is multiplicative.