(noch nicht übersetzt)
Problem 920
For a positive integer n we define τ(n) to be the count of the divisors of n. For example, the divisors of 12 are {1,2,3,4,6,12} and so τ(12)=6.
A positive integer n is a tau number if it is divisible by τ(n). For example τ(12)=6 and 6 divides 12 so 12 is a tau number.
Let m(k) the the smallest tau number x such that τ(x)=k. For example, m(8)=24, m(12)=60 and m(16)=384.
Further define M(n) to be the sum of all m(k) whose values do not exceed 10n. You are given M(3)=3189.
Find M(16).