Products of Bi-Unitary Divisors (noch nicht übersetzt)
Problem 861
A unitary divisor of a positive integer n is a divisor d of n such that gcd(d,nd)=1.
A bi-unitary divisor of n is a divisor d for which 1 is the only unitary divisor of d that is also a unitary divisor of nd.
For example, 2 is a bi-unitary divisor of 8, because the unitary divisors of 2 are {1,2}, and the unitary divisors of 8/2 are {1,4}, with 1 being the only unitary divisor in common.
The bi-unitary divisors of 240 are {1,2,3,5,6,8,10,15,16,24,30,40,48,80,120,240}.
Let P(n) be the product of all bi-unitary divisors of n. Define Qk(N) as the number of positive integers 1<n≤N such that P(n)=nk. For example, Q2(102)=51 and Q6(106)=6189.
Find ∑10k=2Qk(1012).