#include using namespace std; using ll = long long; const ll mod = 1e9 + 7; #define MOD 1000000007 template struct ModInt{ int x; ModInt():x(0){} ModInt(long long y):x(y>=0?y%mod:(mod-(-y)%mod)%mod){} ModInt &operator+=(const ModInt &p){ if((x+=p.x)>=mod)x-=mod; return *this; } ModInt &operator-=(const ModInt &p){ if((x+=mod-p.x)>=mod)x-=mod; return *this; } ModInt &operator*=(const ModInt &p){ x=(int)(1LL*x*p.x%mod); return *this; } ModInt &operator/=(const ModInt &p){ *this*=p.inverse(); return *this; } ModInt &operator^=(long long p){ ModInt res = 1; for (; p; p >>= 1) { if (p & 1) res *= *this; *this *= *this; } return *this = res; } 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;} ModInt operator^(long long 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;} explicit operator int() const { return x; } ModInt operator=(const int p) {x = p; return ModInt(*this);} ModInt inverse()const{ int a=x,b=mod,u=1,v=0,t; while(b>0){ t=a/b; a-=t*b; std::swap(a,b); u-=t*v; std::swap(u,v); } return ModInt(u); } friend std::ostream &operator<<(std::ostream &os,const ModInt &p){ return os<>(std::istream &is,ModInt &a){ long long x; is>>x; a=ModInt(x); return (is); } }; typedef ModInt mint; struct MComb { std::vector fact; std::vector inversed; MComb(int n) { // O(n+log(mod)) fact = std::vector(n+1,1); for (int i = 1; i <= n; i++) fact[i] = fact[i-1]*mint(i); inversed = std::vector(n+1); inversed[n] = fact[n] ^ (MOD-2); for (int i = n - 1; i >= 0; i--) inversed[i]=inversed[i+1]*mint(i+1); } mint ncr(int n, int r) { if (n < r) return 0; if (n < 0 || r < 0) return 0; return (fact[n] * inversed[r] * inversed[n-r]); } mint npr(int n, int r) { if (n < r) return 0; if (n < 0 || r < 0) return 0; return (fact[n] * inversed[n-r]); } mint nhr(int n, int r) { assert(n+r-1 < (int)fact.size()); return ncr(n+r-1, r); } mint fac(int n) { if(n < 0)return 0; return fact[n]; } }; MComb comb(200000); mint ncr(int n, int r) { mint res = 1; for (int i = n - r + 1; i <= n; i++) res *= i; for (int i = 1; i <= r; i++) res /= i; return res; } int main() { int p, k; cin >> p >> k; vector> dp(k + 1, vector(2)); dp[0][0] = 1; for(int i = 0; i < k; i++) { dp[i + 1][0] = dp[i][0] * (p + 1) + dp[i][1] * 2 * (p - 1); // dp[i + 1][0] は dp[i][0]から0から掛けて遷移する通りがP個 + 足し算が1個 非零から足し算と掛け算 dp[i + 1][1] = dp[i][0] + dp[i][1] * 2 * (p - 1); //dp[i + 1][1]はdp[i][0]から足し算で一個, dp[i][1]から掛け算と割り算で(p-1)こずつ } cout << (dp[k][0]) << endl; } //本質は非零に共通点があること