// Errichto
#include<bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i = (a); i <= (b); ++i)
#define RI(i,n) FOR(i,1,(n))
#define REP(i,n) FOR(i,0,(n)-1)
 
const int mod = 1e9 + 7;
 
int main() {
	int n;
	scanf("%d", &n);
	long long s = 0;
	RI(i, n) {
		int a;
		scanf("%d", &a);
		if(n == 1) {
			printf("%d\n", a);
			return 0;
		}
		s = (s + (long long) a * (i + 1)) % mod;
	}
	REP(_, n - 2) s = 2 * s % mod;
	printf("%d\n", (int) s);
	return 0;
}
 

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