There is a set including all positive integers that are not more then $n$. HazelFan wants to choose some integers from this set, satisfying: 1. The number of integers chosen is at least $1$ and at most $k$. 2. The product of integers chosen is 'free from square', which means it is divisible by no square number other than 1. Now please tell him how many ways are there to choose integers, module 10^9+7.