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You are given positive integers $N$ and $M$ .

How many sequences a of length N consisting of positive integers satisfy $a_1 \times a_2 \times ... \times a_n = M$ ?

Here , two sequences $a'$ and $a''$ are considered different when there exists some $i$ such that $ai' != ai''$ .

For example $N = 2$ and $M = 6$, the answer is $4$.

$\{a_1 , a_2 \} = \{ (1,6) (2,3) (3,2) (6,1) \}$

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The different prime factors are independent.
In your example, the 2 could appearas $(1,2)$ or $(2,1)$, and the 3 could be $(1,3)$ or $(3,1)$. Multiply them together, for example $(1,2)\times(1,3)=(1\times1,2\times3)=(1,6)$.
Now how many ways can $p^k$ be placed in $N$ spots? This is a good use of stars and bars.

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