N = int(input())
x = list(map(int,input().split()))

s, s1 = 0, 0
for v in x:
    s1 += s * v
    s += v

d, div = s, 1
for i in range(30):
    if 1000000005 >> i & 1:
        div *= d
        div %= 1000000007
    d *= d
    d %= 1000000007

print((1 + 2 * s1 * div) % 1000000007)