#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

long power(long base, int exponent){
    if(exponent % 2){
        return power(base, exponent - 1) * base % long(1e9 + 7);
    }else if(exponent){
        long root_ans = power(base, exponent / 2);
        return root_ans * root_ans % long(1e9 + 7);
    }else{
        return 1;
    }
}

vector<long> factorial{1};
vector<long> factorial_inverse_element{1};

long combination(int n, int r){
    return factorial[n] * factorial_inverse_element[r] % long(1e9 + 7) * factorial_inverse_element[n - r] % long(1e9 + 7);
}

int main(){
    long n;
    int k;
    cin >> n >> k;
    for(long i = 1; i < 1e5; i++){
        factorial.push_back(factorial.back() * i % long(1e9 + 7));
        factorial_inverse_element.push_back(power(factorial.back(), 1e9 + 5));
    }
    long bernoulli_numbers[k + 1];
    bernoulli_numbers[0] = 1;
    for(int i = 1; i <= k; i++){
        bernoulli_numbers[i] = 0;
        for(int j = 0; j < i; j++){
            if(j % 2){
                bernoulli_numbers[i] += bernoulli_numbers[j] * combination(i + 1, j) % long(1e9 + 7);
            }else{
                bernoulli_numbers[i] += long(1e9 + 7) - bernoulli_numbers[j] * combination(i + 1, j) % long(1e9 + 7);
            }
        }
        bernoulli_numbers[i] %= long(1e9 + 7);
        if(i % 2){
            bernoulli_numbers[i] *= long(1e9 + 7) - power(combination(i + 1, i), 1e9 + 5);
        }else{
            bernoulli_numbers[i] *= power(combination(i + 1, i), 1e9 + 5);
        }
        bernoulli_numbers[i] %= long(1e9 + 7);
    }
    long ans = 0;
    for(int i = 0; i <= k; i++){
        ans += combination(k + 1, i) * bernoulli_numbers[i] % long(1e9 + 7) * power(n % long(1e9 + 7), k + 1 - i) % long(1e9 + 7);
    }
    cout << ans % long(1e9 + 7) * power(k + 1, 1e9 + 5) % long(1e9 + 7) << endl;
}