#include<bits/stdc++.h>

int main(){
    using namespace std;
    constexpr unsigned long MOD{1000000007};
    unsigned long N;
    cin >> N;
    const auto mul_mod{[](auto a, auto b){return a * b % MOD;}};
    vector<unsigned long> A(N);
    for(auto&& i : A)cin >> i;
    inclusive_scan(begin(A), end(A), begin(A), mul_mod);
    vector<unsigned long> coef(N, 3);
    coef.back() = 1;
    coef.rbegin()[1] = 2;
    inclusive_scan(rbegin(coef), rend(coef), rbegin(coef), mul_mod);
    cout << inner_product(begin(A), end(A), begin(coef), 0, plus<>{}, mul_mod) % MOD << endl;
    return 0;
}