#include <bits/stdc++.h>
using namespace std;

typedef long long   signed int LL;
typedef long long unsigned int LU;

#define incID(i, l, r) for(int i = (l)    ; i <  (r); i++)
#define incII(i, l, r) for(int i = (l)    ; i <= (r); i++)
#define decID(i, l, r) for(int i = (r) - 1; i >= (l); i--)
#define decII(i, l, r) for(int i = (r)    ; i >= (l); i--)
#define  inc(i, n) incID(i, 0, n)
#define inc1(i, n) incII(i, 1, n)
#define  dec(i, n) decID(i, 0, n)
#define dec1(i, n) decII(i, 1, n)

#define inII(v, l, r) ((l) <= (v) && (v) <= (r))
#define inID(v, l, r) ((l) <= (v) && (v) <  (r))

#define PB push_back
#define EB emplace_back
#define MP make_pair
#define FI first
#define SE second
#define PQ priority_queue

#define  ALL(v)  v.begin(),  v.end()
#define RALL(v) v.rbegin(), v.rend()
#define  FOR(it, v) for(auto it =  v.begin(); it !=  v.end(); ++it)
#define RFOR(it, v) for(auto it = v.rbegin(); it != v.rend(); ++it)

template<typename T> bool   setmin(T & a, T b) { if(b <  a) { a = b; return true; } else { return false; } }
template<typename T> bool   setmax(T & a, T b) { if(b >  a) { a = b; return true; } else { return false; } }
template<typename T> bool setmineq(T & a, T b) { if(b <= a) { a = b; return true; } else { return false; } }
template<typename T> bool setmaxeq(T & a, T b) { if(b >= a) { a = b; return true; } else { return false; } }
template<typename T> T gcd(T a, T b) { return (b == 0 ? a : gcd(b, a % b)); }
template<typename T> T lcm(T a, T b) { return a / gcd(a, b) * b; }

// ---- ----

LL MOD;
LL mod(LL x, LL m = MOD) { return (x % m + m) % m; }
pair<LL, LL> ex_gcd(LL a, LL b) {
	if(b == 0) { return MP(1, 0); }
	auto p = ex_gcd(b, a % b);
	return MP(p.SE, p.FI - (a / b) * p.SE);
}
LL inv(LL x, LL m = MOD) {
	assert(gcd(x, m) == 1);
	auto p = ex_gcd(x, m);
	return mod(p.FI, m);
}
LL promod(LL x, LL y, LL m = MOD) { return mod((x % m) * (y % m), m); }
LL divmod(LL x, LL y, LL m = MOD) { return promod(x, inv(y, m), m); }

// ----

struct CombMod {
	LL lim = 0, mod;
	LL * fact; // fact[i]: i の階乗
	LL * finv; // finv[i]: i の階乗の逆元
	
	CombMod() { }
	CombMod(LL lim, LL mod = MOD) { init(lim, mod); }
	void init(LL arg_lim, LL arg_mod = MOD) {
		lim = arg_lim;
		mod = arg_mod;
		fact = new LL[lim + 1];
		finv = new LL[lim + 1];
		fact[0] = 1;
		inc1(i, lim) { fact[i] = promod(fact[i - 1], i, mod); }
		finv[lim] = inv(fact[lim], mod);
		dec(i, lim) { finv[i] = promod(finv[i + 1], i + 1, mod); }
	}
	LL P(LL a, LL b) {
		assert(inII(a, 0, lim) && inII(b, 0, lim));
		return (a < b ? 0 : promod(fact[a], finv[a - b], mod));
	}
	LL C(LL a, LL b) {
		assert(inII(a, 0, lim) && inII(b, 0, lim));
		return (a < b ? 0 : promod(P(a, b), finv[b], mod));
	}
	LL H(LL a, LL b) {
		assert(inII(a, 0, lim) && inII(b, 0, lim) && inII(a + b - 1, -1, lim));
		return (a == 0 ? (b == 0) : C(a + b - 1, b));
	}
};

// ----

LL ex(LL x, LL y, LL mod = MOD) {
	LL z[64], v = 1;
	inc(i, 64) { z[i] = (i == 0 ? x : z[i - 1] * z[i - 1]) % mod; }
	inc(i, 64) { if((y >> i) & 1) { (v *= z[i]) %= mod; } }
	return v;
}

// ----

const int LIM = 10000;
LL B[LIM + 2];
CombMod cm;
void calc_bernoulli_number_mod(LL n, LL m, int sgn = -1) { // calc: [0, n], m: prime number
	// sgn == -1: B-  (B(1) == -1/2)
	// sgn == +1: B+  (B(1) == +1/2)
	assert(abs(sgn) == 1);
	
	incII(i, 0, n) {
		if(i == 0) { B[0] = 1; }
		else {
			B[i] = 0;
			inc(k, i) { (B[i] += cm.C(i + 1, k) * B[k]) %= m; } // ここが遅すぎて TLE
			B[i] = divmod(-B[i], i + 1, m);
		}
	}
	if(sgn == +1) { B[1] = divmod(+1, 2, m); }
}

LL sum_power(LL n, LL k, LL m) { // (1^k + 2^k + ... + n^k) % m
	assert(k <= LIM);
	
	cm.init(k + 1, m);
	calc_bernoulli_number_mod(k, m, +1);
	
	LL ans = 0;
	incII(i, 0, k) { (ans += cm.C(k + 1, i) * B[i] % m * ex(n, k + 1 - i, m)) %= m; }
	return divmod(ans, k + 1, m);
}

int main() {
	LL n, k;
	cin >> n >> k;
	
	cout << sum_power(n, k, 1e9 + 7) << endl; 
	
	return 0;
}