// Validator
#include "testlib.h"
#include <iostream>
#include <vector>
using namespace std;
#include <atcoder/modint>
using mint = atcoder::modint1000000007;

int main(int argc, char **argv) {
    registerValidation(argc, argv);
    int N = inf.readInt(2, 200000);
    inf.readEoln();
    vector<int> A = inf.readInts(N, 0, 1000000000);
    inf.readEoln();
    inf.readEof();

    mint ret = 0, prod = 1;
    const mint d23 = mint(2) / 3;
    for (int i = 0; i < N; i++) {
        ret *= 3;
        prod *= A[i];
        ret += prod * (i == N - 1 ? 1 : d23);
    }
    cout << ret.val() << '\n';
}