#include <bits/stdc++.h>
using namespace std;

struct iofast_t {
    iofast_t() {
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
    }
} iofast;

struct uns_t {} uns;
template <typename Element, typename Head, typename ...Args>
auto vec(Element init, Head arg, Args ...args) {
    if constexpr (sizeof...(Args) == 0) return std::vector(arg, init);
    else return std::vector(arg, vec(init, args...));
}
template <typename Element, typename Head, typename ...Args>
auto vec(uns_t, Head arg, Args ...args) {
    return vec(Element(), arg, args...);
}

template <typename T, typename Compare = less<T>>
T &chmin(T &l, T r, Compare &&f = less<T>()) { return l = min(l, r, f); }
template <typename T, typename Compare = less<T>>
T &chmax(T &l, T r, Compare &&f = less<T>()) { return l = max(l, r, f); }

#include <atcoder/modint>
using mint = atcoder::modint1000000007;

int main() {
    int n; cin >> n;
    auto a = vec<int>(uns, n);
    for (auto &e : a) cin >> e;

    mint ans = 0, acc = 1;
    for (int i = 0; i < n; ++i) {
        acc *= a[i];
        ans += acc * (2 - (i + 1 == n)) * mint(3).pow(max(0, n - 2 - i));
    }

    cout << ans.val() << endl;
}