N = int(input())
A = list(map(int,input().split()))
MOD = 10**9+7

p2 = [1]
p3 = [1]
for _ in range(N+10):
    p2.append(p2[-1]*2%MOD)
    p3.append(p3[-1]*3%MOD)
for _ in range(10):
    p3.append(1)

ans = 0
t = 1
for i in range(N):
    t *= A[i]
    t %= MOD
    tmp = t*p3[N-i-2]%MOD
    if i != N-1:
        tmp*=2
    ans += tmp
    ans %= MOD
print(ans)