#include <bits/stdc++.h>
#define int long long
#define mod 1000000007
using namespace std;
const int MAXN = 2e5 + 10;
int n,a[200005],ans,sum[200005];
int qpow(int x,int y){
	int ans=1;
	while(y){
		if(y&1){
			(ans*=x)%mod;
		}
		(x*=x)%=mod;
		y>>=1;
	}
	return ans;
}
void solve(){
	sum[0]=1;
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>a[i];
		sum[i]=sum[i-1]*a[i]%mod;
	}
	for(int i=1;i<n;i++){
		(ans+=sum[i]*2*qpow(3,n-i-1))%=mod;
	}
	(ans+=sum[n])%=mod;
	cout<<ans;
}
signed main(){
	solve();
}