n = int(input())
a = list(map(int, input().split()))

MOD = 998244353

pow2 = pow(2, (MOD - 1) + (n - 3), MOD)

res = 0
for i in range(n):
    res += pow2 * a[i] * (i + 2) * (n - i + 1)

print(res % MOD)