#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define ll long long int #define pb push_back #define rep(i,n) for(int i=0;i<(n);i++) #define REP(i,n) for(int i=1;i<=(n);i++) using namespace std; int mx8[] = {0,0,1,-1,-1,1,-1,1}; int my8[] = {-1,1,0,0,-1,-1,1,1}; int mx4[] = {1,-1,0,0}; int my4[] = {0,0,-1,1}; //ll mod = 1000000009; const int MAX = 510000; const int MOD = 1000000007; long long fac[MAX], finv[MAX], inv[MAX]; // テーブルを作る前処理 void COMinit() { 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; } } // 二項係数計算 long long COM(int n, int k) { if (n < k) return 0; if (n < 0 || k < 0) return 0; return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD; } int main() { int n; cin >> n; vector a(n); rep(i,n) cin >> a[i]; COMinit(); ll ans = 0; rep(i,n){ ans += COM(n-1,i) * a[i] % MOD; } cout << ans % MOD << endl; }