import sys
input=sys.stdin.readline
def I(): return int(input())
def MI(): return map(int, input().split())
def LI(): return list(map(int, input().split()))

def main():
    mod=10**9+7
    N=I()
    A=LI()
    
    def sum2(x):
        return (x*(x+1))//2
    
    def calc(k):#k番目
        temp=sum2(k-1)*2
        temp+=k*(N-(k-1)*2)
        return temp
    
    ans=0
    for i in range(N):
        d=calc(i+1)
        ans+=d*A[i]
        
    print(ans)
        


main()