n = int(input())
a = list(map(int,input().split()))
ans = 0
mod = 10 ** 9 + 7
buf = pow(3,n-1,mod) * pow(3,mod-2,mod) * 2
buf2 = 1
for i in range(n):
    buf2 *= a[i]
    buf2 %= mod
    if i == 0:
        ans += buf * buf2
#         print(ans,"a")
    elif i != n - 1:
        buf *= pow(3,mod-2,mod)
        buf %= mod
        ans += buf * buf2
        ans %= mod
    else:
        ans += buf2
        ans %= mod
#     print(ans)
print(ans)