#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
template<class T> bool chmax(T &a, T b){if (a < b){a = b;return true;} else return false;}
template<class T> bool chmin(T &a, T b){if (a > b){a = b;return true;} else return false;}

using ll=unsigned long long;

const ll MOD=1e9+7;
const int MAX=2e4+10;
vector<ll>fac(MAX),finv(MAX),inv(MAX);

void set_fac(){
    fac[0]=fac[1]=1;
    finv[0]=finv[1]=1;
    inv[1]=1;
    for (int i=2;i<MAX;i++){
        fac[i]=fac[i-1]*i%MOD;
        inv[i]=MOD-inv[MOD%i]*(MOD/i)%MOD;
        finv[i]=finv[i-1]*inv[i]%MOD;
    }
}

ll cmb(int n,int r){
    if (r<0||n<r)return 0;
    return fac[n]*(finv[r]*finv[n-r]%MOD)%MOD;
}

ll power(ll x,ll r){
    ll re=1,k=x;
    for(int i=0;i<60;i++){
        if(r>>i&1){
            re=(re*k)%MOD;
        }
        k=k*k%MOD;
    }
    return re;
}

ll modinv(ll x){
    return power(x, MOD-2);
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    set_fac();
    ll N;
    int K;
    cin>>N>>K;
    vector<ll>dp(K+1);
    dp[0]=N%MOD;
    ll P=(N+1)%MOD;
    for(int i=1;i<=K;i++){
        P*=(N+1)%MOD;
        P%=MOD;
        dp[i]=P-1;
        for(int j=2;j<=i+1;j++){
            dp[i]+=MOD-cmb(i+1,j)*dp[i+1-j]%MOD;
            dp[i]%=MOD;
        }
        dp[i]*=inv[i+1];
        dp[i]%=MOD;
    }
    cout<<dp[K]<<"\n";
}