//GIVE ME AC!!!!!!!!!!!!!!!!!
//#pragma GCC target("avx")
//#pragma GCC optimize("O3")
//#pragma GCC optimize("unroll-loops")
#include<bits/stdc++.h>
#define ll long long
#define ld long double
#define floatset() fixed<<setprecision(15)
#define all(n) n.begin(),n.end()
#define rall(n) n.rbegin(),n.rend()
#define rep(i, s, n) for (ll i = s; i < (ll)(n); i++)
#define pb push_back
#define eb emplace_back
#define max_(a) *max_element(all(a))
#define min_(a) *min_element(all(a))
#define INT(...) int __VA_ARGS__;scan(__VA_ARGS__)
#define LL(...) ll __VA_ARGS__;scan(__VA_ARGS__)
#define STR(...) string __VA_ARGS__;scan(__VA_ARGS__)
#define CHR(...) char __VA_ARGS__;scan(__VA_ARGS__)
#define DBL(...) double __VA_ARGS__;scan(__VA_ARGS__)
#define LD(...) ld __VA_ARGS__;scan(__VA_ARGS__)
using namespace std;
using vl=vector<ll>;
using vi=vector<int>;
using vs=vector<string>;
using vc=vector<char>;
using vvl=vector<vl>;
using P=pair<ll,ll>;
using vvc=vector<vc>;
using vd=vector<double>;
using vp=vector<P>;
using vb=vector<bool>;
const int dx[8]={1,0,-1,0,1,-1,-1,1};
const int dy[8]={0,1,0,-1,1,1,-1,-1};
const ll inf=2e18;
const ll MOD=1000000007;
const ll mod=998244353;
const double pi=acos(-1);
template<typename T1,typename T2 >
ostream &operator<<(ostream&os,const pair<T1,T2>&p) {
  os<<p.first<<" "<<p.second;
  return os;
}
template<typename T1,typename T2>
istream &operator>>(istream&is,pair<T1,T2>&p) {
  is>>p.first>>p.second;
  return is;
}
template<typename T>
ostream &operator<<(ostream&os,const vector<T>&v) {
  for(int i=0;i<(int)v.size();i++) {
    os<<v[i]<<(i+1!=v.size()?" ":"");
  }
  return os;
}
template<typename T>
istream &operator>>(istream&is,vector<T>&v) {
  for(T &in:v)is>>in;
  return is;
}
void scan(){}
template<class Head,class... Tail>
void scan(Head&head,Tail&... tail) {
  cin>>head;
  scan(tail...);
}
template<class T>
void print(const T &t) { cout << t << '\n'; }
template<class Head, class... Tail>
void print(const Head &head, const Tail &... tail) {
  cout << head << ' ';
  print(tail...);
}
template<class... T>
void fin(const T &... a) {
  print(a...);
  exit(0);
}
template<typename T>
ll sum_(vector<T>&v){
  ll res=0;
  for(auto &e:v)res+=e;
  return res;
}
template<typename T1,typename T2>
inline bool chmax(T1&a,T2 b){return a<b&&(a=b,true);}
template<typename T1,typename T2>
inline bool chmin(T1&a,T2 b){return a>b&&(a=b,true);}
template<long long m>
struct modint{
  long long x;
  modint():x(0){}
  modint(long long y):x(y>=0?y%m:(m-(-y)%m)%m){}
  modint inv()const{long long a=x,b=m,u=1,v=0,t;
    while(b){
      t=a/b;
      swap(a-=t*b,b);
      swap(u-=t*v,v);
    }
    return modint(u);
  }
  modint &operator+=(const modint&p) {if((x+=p.x)>=m)x-=m;return *this;}
  modint &operator-=(const modint&p){if((x+=m-p.x)>=m)x-=m;return *this;}
  modint &operator*=(const modint&p) {x=x*p.x%m;return *this;}
  modint &operator/=(const modint&p){*this*=p.inv();return *this;}
  modint operator-()const{return modint(-x); }
  modint operator+(const modint&p)const{return modint(*this)+=p; }
  modint operator-(const modint&p)const{return modint(*this)-=p; }
  modint operator*(const modint&p)const{return modint(*this)*=p; }
  modint operator/(const modint&p)const{return modint(*this)/=p; }
  bool operator==(const modint&p)const{return x==p.x;}
  bool operator!=(const modint&p)const{return x!=p.x;}
  modint pow(long long n) const {
    modint ret(1),mul(x);
    while(n){
      if(n&1)ret*=mul;
      mul*=mul;
      n>>=1;
    }
    return ret;
  }
  friend ostream &operator<<(ostream &os,const modint&p) {
    return os<<p.x;
  }
  friend istream &operator>>(istream &is, modint &a) {
    long long t;
    is>>t;
    a=modint<m>(t);
    return (is);
  }
  static long long get_mod(){return m;}
};
template<long long m>
struct combination{
  using mint=modint<m>;
  vector<mint>dat,idat;
  long long mx;
  combination(long long mx_=300000):dat(mx_+1,1),idat(mx_+1,1),mx(mx_){
    for(long long i=1;i<=mx;i++)dat[i]=dat[i-1]*mint(i);
    idat[mx]/=dat[mx];
    for(long long i=mx;i>0;i--)idat[i-1]=idat[i]*mint(i);
  }
  mint com(long long n,long long k){
    if(n<0||k<0||n<k)return mint(0);
    return dat[n]*idat[k]*idat[n-k];
  }
  mint fac(long long n){
    if(n<0)return mint(0);
    return dat[n];
  }
};
template<long long m>
modint<m> lagrange_polynominal(vector<modint<m>>&y,long long t){
  using mint=modint<m>;
  long long n=y.size()-1;
  combination<m>c;
  if(t<=n)return y[t];
  mint ret;
  vector<mint>dp(n+1,1),pd(n+1,1);
  for(int i=0;i<n;i++)dp[i+1]=dp[i]*(t-i);
  for(int i=n;i>0;i--)pd[i-1]=pd[i]*(t-i);
  for(int i=0;i<=n;i++){
    mint tmp=y[i]*dp[i]*pd[i]*c.idat[i]*c.idat[n-i];
    if((n-i)&1)ret-=tmp;
    else ret+=tmp;
  }
  return ret;
}
using mint=modint<MOD>;
int main(){
  LL(n,k);
  vector<mint>v(k+2);
  rep(i,1,k+2){
    v[i]=v[i-1]+mint(i).pow(k);
  }
  fin(lagrange_polynominal(v,n));
}