#include using namespace std; typedef long long ll; #define REP(i,n) for(int i=0; i #define VLL vector #define VVI vector> #define VVLL vector> #define VC vector #define VS vector #define VVC vector> #define fore(i,a) for(auto &i:a) typedef pair P; template bool chmax(T &a, T b) { if (a < b) { a = b; return true; } return false; } template bool chmin(T &a, T b) { if (a > b) { a = b; return true; } return false; } const int INF = 1 << 30; const ll INFL = 1LL<<60; const ll mod = 1000000007; const int MAX = 510000; 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() { COMinit(); int n; cin >> n; VLL v(n); REP(i, n)cin >> v[i]; ll ans = 0; REP(i, n) { ans += COM(n-1, i)*v[i]; ans %= mod; } cout << ans << endl; }