# coding: utf-8
# Your code here!
def Eratosthenes(N): #N以下の素数のリストを返す
    #iが素数のときis_prime_list[i]=1，それ以外は0
    N+=1
    is_prime_list = [True]*N
#    is_prime_list[0], is_prime_list[1] = False, False #リストが必要なときはこの2行を有効化
#    for j in range(4,N,2): is_prime_list[j] = False
    m = int(N**0.5)+1
    for i in range(3,m,2):
        if is_prime_list[i]:
            is_prime_list[i*i::2*i]=[False]*((N-i*i-1)//(2*i)+1)
    return [2] + [i for i in range(3,N,2) if is_prime_list[i]]
#    return is_prime_list

import sys
#sys.setrecursionlimit(10**6)
readline = sys.stdin.readline 

n = int(input())
a = [int(i) for i in readline().split()]
ra = list(reversed(a))

p2 = [1,4]
if n >= 4:
    while 2*p2[-1] <= n:
        p2.append(p2[-1]*2)

from itertools import accumulate
primes = Eratosthenes(n)+p2

#print(primes)

def ans(k,a,ra):
    res1 = []
    R1 = [0]
    for i in range(k,n+1,k):
        l = a[i-k:i]
        l.sort()
        res1.append(l[(k+1)//2-1])
    for i in accumulate(res1):
        R1.append(max(R1[-1],i))

#    print(res1,R1)

    res2 = []
    R2 = [0]
    for i in range(k,n+1,k):
        l = ra[i-k:i]
        l.sort()
        res2.append(l[(k+1)//2-1])
    for i in accumulate(res2):
        R2.append(max(R2[-1],i))
#    print(res2,R2)
    
    res1 = R1
    res2 = R2
        
    res = 0    
    for r1,r2 in zip(res1,reversed(res2)):
        res = max(res,r1+r2)
#    print(res*k)
    return(res*k)

c = 0
for p in primes:
    c = max(c,ans(p,a,ra))

print(c)