#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using ll=long long;
using Graph=vector<vector<int>>;
#define MAX 2000005
#define MOD 1000000007
//#define MOD 998244353
#define INF 1000000000
//#define INF 1000000000000000000

int main(){
  int N;
  cin>>N;
  vector<int> A(N);
  for(int i=0;i<N;i++){
    cin>>A[i];
  }
  vector<ll> pow2(N+1,1);
  vector<ll> pow3(N+1,1);
  for(int i=1;i<=N;i++){
    pow2[i]=2*pow2[i-1]%MOD;
    pow3[i]=3*pow3[i-1]%MOD;
  }
  ll ans=0;
  ll x=1;
  for(int i=0;i<N-1;i++){
    x=x*A[i]%MOD;
    ans+=x*2*pow3[N-2-i];
    ans%=MOD;
  }
  x=x*A[N-1]%MOD;
  ans+=x;
  ans%=MOD;
  cout<<ans<<'\n';

}