N=int(input())
A=list(map(int,input().split()))
mod=998244353
if N==1:
    ans=A[0]
else:
    cnt=[None]*N
    for i in range(N):
        cnt[i]=pow(2,N-2,mod)*(1+mod)//2*(min(i,N-1-i)+2)*(N+1-min(i,N-1-i))%mod
    ans=sum(a*c for a,c in zip(A,cnt))%mod
print(ans)