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

long long n, m = 0, t = 1;
long long a[200000];
const long long M = 1e9 + 7;

long long powm(long long a, long long b) {
	long long u = 1, v = a;

	while (b > 0) {
		if (b & 1)
			u = u * v % M;

		v = v * v % M;
		b >>= 1;
	}

	return u;
}

int main()
{
	cin >> n;

	for (int i = 0; i < n; i++)
		cin >> a[i];

	for (int i = 0; i < n; i++) {
		t = t * a[i] % M;

		if(i < n - 1)
			m = (m + t * powm(3, n - 2 - i) * 2 % M) % M;
		else
			m = (m + t) % M;
	}

	cout << m << endl;
}