n = int(input())
a = [int(i) for i in input().split()]

mod = 10**9+7

def c(n,k): 
    if(k<=0 or n<=k):
        return 1
    else:
        return(c(n-1, k-1) + c(n-1, k))

ans = 0
for i in range(n):
    ans += c(n-1,i)*a[i]
    ans %= mod

print(ans)