#include using namespace std; using ll = long long; using VI = vector; using VL = vector; using PII = std::pair; using PLL = std::pair; #define rep(i, n) for (int i = 0; i < (int)(n); i++) #define repr(i, n) for (int i = (int)(n)-1; i >= 0; i--) #define rep2(i, s, n) for (int i = (s); i < (int)(n); i++) #define allpt(v) (v).begin(), (v).end() #define allpt_r(v) (v).rbegin(), (v).rend() const int mod = 1e9 + 7; const string wsp = " "; const string tb = "\t"; const string rt = "\n"; template void show1dvec(vector v) { if (v.size() == 0) return; int n = v.size() - 1; rep(i, n) cout << v[i] << wsp; cout << v[n] << rt; return; } template void show2dvec(vector> v) { int n = v.size(); rep(i, n) show1dvec(v[i]); } bool in_field(int h, int w, int y, int x) { return 0 <= y && y < h && 0 <= x && x < w; } ll pow_mod(int p, int q, int mod) { ll ret, r; ret = 1; r = p; while (q > 0) { if (q % 2) { ret *= r; ret %= mod; } r = (r * r) % mod; q /= 2; } return ret % mod; } int main() { #ifdef DEBUG cout << "DEBUG MODE" << endl; ifstream in("input.txt"); //for debug cin.rdbuf(in.rdbuf()); //for debug #endif int n; ll ans = 0, a, s; cin >> n; VL comb(n, 1); rep(i, n - 1) { s = n - i - 1; s *= pow_mod(i + 1, mod - 2, mod); s %= mod; comb[i + 1] = comb[i] * s; comb[i + 1] %= mod; } rep(i, n) { cin >> a; ans += (a * comb[i]) % mod; ans %= mod; } cout << ans << rt; return 0; }