#include <bits/stdc++.h>
using i64 = long long;

const i64 mod = 1e9 + 7;
const int maxn = 1e5 + 5;

i64 power(i64 x,i64 y) {
	i64 ans = 1;
	for(;y;y >>= 1) {
		if(y & 1)(ans *= x) %= mod;
		(x *= x) %= mod;
	}
	return ans;
}

int n,a[maxn];
i64 f[maxn];

int main() {
	freopen("sequenceQBXT.in","r",stdin);
	freopen("sequenceQBXT.out","w",stdout);
	scanf("%d",&n);
	i64 pw = power(2 , mod - 2);
	for(int i = 1;i <= n;++ i)
		scanf("%d",&a[i]);
	i64 ans = f[1] = a[1];
	for(int i = 2;i <= n;++ i) {
		(ans += 1ll * pw * a[i] % mod + 1ll * pw * (a[i] - 1) % mod * f[i - 1] % mod) %= mod;
		f[i] = (1ll * pw * a[i] % mod + 1ll * pw * a[i] % mod * f[i - 1] % mod) % mod;
	}
	printf("%lld\n",ans * power(2 , n - 1) % mod);
	return 0;
}