summy_70

#include <iostream>
#define MOD 1000000007
using namespace std;

int lgput(int n,int p)
{
    int na=1;
    while(p)
    {
        if(p%2==1)
            na=1LL*na*n%MOD;
        n=1LL*n*n%MOD;
        p/=2;
    }
    return na;
}

int main()
{
    int n,k,s=1;
    cin>>n>>k;
    for(int i=2;i<=n;++i)
        s+=lgput(i,k),s%=MOD;
    cout<<s;
    return 0;
}