from itertools import accumulate
N=int(input())
A=list(map(int,input().split()))
mod=10**9+7
for i in range(N-1):
  A[i+1]=A[i]*A[i+1]%mod
ans=0
for i in range(N-1):
  ans+=A[i]*(pow(3,N-i-1,mod)-pow(3,N-i-2,mod))%mod
print((ans+A[-1])%mod)