/**
 *    author:  Sooh
 *    created: 17.09.2021 22:05:56
**/
#include<bits/stdc++.h>
using namespace std;
#if __has_include(<atcoder/all>)
#include <atcoder/all>
using namespace atcoder;
//using mint = modint998244353;
//using mint = modint1000000007;
#endif
#pragma region template
using ll = long long;
template <class T> using V = vector<T>;
#define rep(i,n) for(int i=0;i<n;++i)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) ((int)(x).size())
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define debug(var)  do{std::cerr << #var << " : ";view(var);}while(0)
template<typename T> void view(T e){std::cerr << e << std::endl;}
template<typename T> void view(const std::vector<T>& v){for(const auto& e : v){ std::cerr << e << " "; } std::cerr << std::endl;}
template<typename T> void view(const std::vector<std::vector<T> >& vv){cerr << endl;int cnt = 0;for(const auto& v : vv){cerr << cnt << "th : "; view(v); cnt++;} cerr << endl;}
ll power(ll a, ll p){ll ret = 1; while(p){if(p & 1){ret = ret * a;} a = a * a; p >>= 1;} return ret;}
ll modpow(ll a, ll p, ll mod){ll ret = 1; while(p){if(p & 1){ret = ret * a % mod;} a = a * a % mod; p >>= 1;} return ret;}
ll modinv(ll a, ll m) {ll b = m, u = 1, v = 0; while (b) {ll t = a / b ;a -= t * b; swap(a, b);u -= t * v; swap(u, v);}u %= m;if (u < 0) u += m;return u;}
template<class T, class K>bool chmax(T &a, const K b) { if (a<b) { a=b; return 1; } return 0; }
template<class T, class K>bool chmin(T &a, const K b) { if (b<a) { a=b; return 1; } return 0; }
#pragma endregion
int dx[]={1,0,-1,0};
int dy[]={0,1,0,-1};
const int inf = 1001001001;
const ll INF = 1001001001001001001ll;
//const double pi = acos(-1);
//const ll mod = 998244353;
const ll mod = 1000000007;

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    //cout << fixed << setprecision(20);
    int n; cin >> n;
    V<ll> a(n);
    rep(i,n) cin >> a[i];
    ll ans = 0;
    V<ll> three(n);
    three[0] = 1;
    for(int i = 1; i < n; i++) three[i] = three[i - 1] * 3 % mod;
    ll tmp = a[0];
    for(int i = 1; i < n; i++){
        ans += tmp * 2 * three[n - i - 1] % mod;
        ans %= mod;
        tmp = tmp * a[i] % mod;
    }
    cout << (tmp + ans) % mod << endl;
}