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

ANS=0
K=1

ALL=pow(3,N-1,mod)

for i in range(N):
    K=K*A[i]%mod

    if i!=N-1:
        ANS=ANS+K*ALL*2*pow(3,mod-2,mod)
    else:
        ANS=ANS+K*ALL
        
    ANS%=mod
    ALL=ALL*pow(3,mod-2,mod)%mod

    #print(ANS,ALL)

print(ANS)