from math import factorial
n=int(input())
a=list(map(int,input().split()))
point=0
def cmb(l,i,j):
    a = factorial(i) / factorial(j-1) / factorial(i-j+1)
    b = 2**(len(l)-i-1)
    return int(a*b)

for i in range(n):
    for j in range(1,i+2):
        point+=a[i]*j*cmb(a,i,j)
print(point%998244353)