If you are asking a question about the mean value of a multiplicative function, I encourage you to read these two answers:

• http://math.stackexchange.com/questions/90120/mean-value-of-a-multiplicative-function-close-to-n-in-terms-of-the-zeta-functi/90125#90125
• http://math.stackexchange.com/questions/84708/prove-sum-limits-n-leq-x-fracn-phin-ox/84721#84721