#include<cstdio>
#include<iostream>

using namespace std;

int main(){

    int n, i, a, j, sum, first, last, higer = -100000, x;
    scanf("%i", &n);
    /*
    if(n > 2){
        x = n;
    }else{
        x = 
    }*/
    int bloques[n-2], sumas[((n-2)/2)+1];

    scanf("%i", &first);
    sumas[0] = -100000;

    for(i = 1; i<n-1; i++){

        scanf("%i", &a);
        //bloques[i] = a;

        if(i<=((n-2)/2)){

            sumas[i] = a;

        }

        else{
            
            if(a>sumas[0]){

                sumas[0] = a;
            }
        } 

        for(j = i/2; j>0; j--){

            if(!((i%(j+1)))){

                sumas[j]+=a;
            }

        }
    }

    scanf("%i", &last);
    
    for(i = 0; i<((n-2)/2)+1; i++){

        if(sumas[i] > higer){

            higer = sumas[i];

        }
    }

    printf("%i\n", higer+first+last);

    return 0;
}