#include <iostream>
#include <iomanip>
#include <string>
#include <vector>
#include <cmath>
#include <cstdlib>
#include <algorithm>
#include <ios>
#include <iomanip>
#include <queue>
#include <numeric>
#include <map>
#include <set>
#include <sstream>
#include <bitset>
#include <climits>
#include <stack>
#include <regex>
#include <functional>
#include <random>
#ifdef _WIN64
#  include <atcoder/all>
#endif
#ifdef _MSC_VER
#  include <intrin.h>
#  define __builtin_popcount __popcnt
#  define __builtin_popcountl __popcnt64
#endif

using namespace std;

#define ll long long
#define rep(i, init, n) for(ll i = init; i < (ll)n; i++)
#define rrep(i, init, n) for(ll i = init; i >= (ll)n; i--)
#define all(x) (x).begin(), (x).end()
#define sz(x) (ll)(x.size())
#define Out(x) cout << x << endl
#define Yes cout << "Yes" << endl
#define No cout << "No" << endl
#define Ans cout << ans << endl
#define PI 3.14159265358979
#define MOD 1000000007

const int inf32 = INT_MAX / 2;
const ll inf64 = 1LL << 60;
template<class T>bool chmax(T &a, const T &b) { if (a < b) { a = b; return true; } return false; }
template<class T>bool chmin(T &a, const T &b) { if (a > b) { a = b; return true; } return false; }

// -------------------------------------------------------------------------------------------------

struct mint
{
	ll x;

	mint(ll val = 0) { x = (val % MOD + MOD) % MOD; }

	mint operator-() const { return mint(-x); }
	mint& operator+=(const mint& other) { x += other.x; if (x >= MOD) x -= MOD; return *this; }
	mint& operator-=(const mint& other) { x -= other.x; if (x < 0) x += MOD; return *this; }
	mint& operator*=(const mint& other) { (x *= other.x) %= MOD; return *this; }
	mint& operator/=(const mint& other) { *this *= other.pow(MOD - 2); return *this; }
	mint operator+(const mint& other) const { return mint(*this) += other; }
	mint operator-(const mint& other) const { return mint(*this) -= other; }
	mint operator*(const mint& other) const { return mint(*this) *= other; }
	mint operator/(const mint& other) const { return mint(*this) /= other; }

	mint pow(ll i) const
	{
		mint ret = 1;
		for (mint tmp = x; i; tmp *= tmp, i >>= 1) if (i & 1) ret *= tmp;
		return ret;
	}

	friend ostream& operator<<(ostream& os, const mint& m) { os << m.x; return os; }
};
ll mpow(ll x, ll y)
{
	if (y == 0) return 1;

	x %= MOD;
	if (x == 0) return 0;

	if (y % 2 == 0) return mpow(x * x % MOD, y / 2) % MOD;
	else return x * mpow(x, y - 1) % MOD;
}

int main()
{
	ll n; cin >> n;
	vector<ll> a(n);
	rep(i, 0, n) cin >> a[i];

	mint mul = 1;
	mint ans = 0;

	rep(i, 0, n)
	{
		mul *= a[i];

		mint tmp = mul;
		if (i < n - 1) tmp *= 2;
		if (i < n - 2) tmp *= mpow(3, n - 2 - i);

		ans += tmp;
	}

	Ans;

	return 0;
}