#include "bits/stdc++.h" using namespace std; const int MOD = 1e9 + 7; #define MAX 100000 #define Rep(b, e, i) for (int i = b; i <= e; i++) #define rep(n, i) Rep(0, n - 1, i) typedef long long ll; //階乗とその逆元 ll fac[MAX + 1], facInv[MAX + 1]; ll power(ll e, ll x) { //e^x % MOD if (x == 0) return 1LL; if (x % 2 != 0) return ((power(e, x - 1) * e) % MOD); ll temp = power(e, x / 2); return (temp * temp) % MOD; } ll nck(ll n, ll k) { if (!(n >= k && k >= 0)) return 0; ll temp = (fac[n] * facInv[n - k]) % MOD; return ((temp * facInv[k]) % MOD); } void fact(void) { //階乗とその逆元 fac[0] = facInv[0] = 1; //0! = 1 //(x!)^(-1) ≡ (x!)^(p-2) (mod p) Rep(1, MAX, i) fac[i] = (fac[i - 1] * i) % MOD; facInv[MAX] = power(fac[MAX], MOD - 2); Rep(1, MAX - 1, i) facInv[MAX - i] = (facInv[MAX - i + 1] * (MAX - i + 1)) % MOD; } void solve() { int N; cin >> N; long ans = 0; fact(); for (int i = 0; i < N; i++) { long a; cin >> a; ans += nck(N-1, i) * a; ans %= MOD; } cout << ans << endl; } int main(void) { solve(); //cout << "yui(*-v・)yui" << endl; return 0; }