import math
import sys
def S(): return sys.stdin.readline().rstrip()
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int, sys.stdin.readline().rstrip().split())
def LI(): return list(map(int, sys.stdin.readline().rstrip().split()))
def LS(): return list(sys.stdin.readline().rstrip().split())

n = I()
a = LI()

ans = 0
for i in range(n):
    ans += math.comb(n-1, i)*a[i]
    ans %= 10**9+7

print(ans)