No.1923 Divisor Array
問題文最終更新日: 2022-05-01 23:50:22
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Problem Statement
You are given positive integers $N,M,K$. Let $D$ be the product of the $K$ smallest prime numbers. How many sequences $A = (A_0, A_1, \dots, A_N)$ of length $N+1$ satisfy the following conditions? Output the answer modulo $998244353$.
Conditions
- $A_0 = D$
- For $i = 1,\dots,N$, $A_i$ is a positive divisor of $\displaystyle\prod_{j = 0}^{i-1}A_j$.
- The number of positive divisors of $\displaystyle\prod_{i = 1}^{N}A_i$ is at most $M$.
Input
$N$ $M$ $K$
- $1 \leq N \leq 10^9$
- $1 \leq M \leq 2000$
- $1 \leq K \leq 10^9$
- All values in the input are integers.
Output
Output the answer modulo $998244353$.
Sample
Sample 1
Input
2 2 2
Output
5
Since $K=2$, we have $D=2\times3$. In this case, the following $5$ sequences $A$ of length $3$ satisfy the conditions.
- $(A_0,A_1,A_2) = (6,1,1)$
- $(A_0,A_1,A_2) = (6,1,2)$
- $(A_0,A_1,A_2) = (6,2,1)$
- $(A_0,A_1,A_2) = (6,1,3)$
- $(A_0,A_1,A_2) = (6,3,1)$
Sample 2
Input
3 3 4
Output
25
Sample 3
Input
1000000000 2000 1000000000
Output
362056892
Note that you should output the answer modulo $998244353$.
Source: CPCTF22
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