打表找规律
对于数学题,打表找规律还是非常有用的!!!!!!
#include<iostream>
#include<algorithm>
using namespace std;
typedef long long ll;
const int max_n= 5e5+100;
const ll mod = 998244353;
ll POW(int a,int p){
ll base = a;
ll ans=1;
while (p){
if (p&1)ans = ans*base%mod;
base = (base*base)%mod;
p>>=1;
}return ans;
}
ll inv(int a){
return POW(a,mod-2);
}
ll j[max_n];
ll C(int n,int m){
if (n<m)return 0;
return j[n]*inv(j[m]*j[n-m]%mod)%mod;
}
int n,k;
int main(){
ios::sync_with_stdio(0);j[0]=1;
cin>>n>>k;
for (int i=1;i<=n;++i)j[i]=j[i-1]*i%mod;
ll ans = 0;
for (int i=1;i<=n;++i)
ans = (ans+C(n/i-1,k-1))%mod;
cout<<ans<<endl;
}