N = int(input())
A = list(map(int, input().split()))
mod = 10 ** 9 + 7
Ac = [1] * N
Ac[0] = A[0]
for i in range(1, N):
    Ac[i] = Ac[i - 1] * A[i]
    Ac[i] %= mod

ans = Ac[N - 1]
now = 2
for i in range(N - 2, -1, -1):
    ans += Ac[i] * now
    now *= 3
    ans %= mod
    now %= mod
print(ans)