#include <bits/stdc++.h>
#define int long long
#define mod (int)(1e9+7)
#define inf (int)(3e18)
#define rep(i,n) for(int i=0;i<n;i++)
#define REP(i,n) for(int i=1;i<n;i++)
#define P std::pair<int,int>
#define PiP std::pair<int,std::pair<int,int>>
#define all(v) v.begin(),v.end()
#define mkp std::make_pair
#define prique(T) std::priority_queue<T,vector<T>,greater<T>>
using namespace std;
template<class T> inline void chmax(T &a, T b) {
	a = std::max(a, b);
}
template<class T> inline void chmin(T &a, T b) {
	a = std::min(a, b);
}

bool prime(int x) {
	for (int i = 2; i * i <= x; i++) {
		if (x % i == 0)
			return false;
	}
	return x != 1;
}
int gcd(int x, int y) {
	if (y == 0)
		return x;
	return gcd(y, x % y);
}
int lcm(int x, int y) {
	return x / gcd(x, y) * y;
}
int kai(int x, int y) {
	int res = 1;
	for (int i = x - y + 1; i <= x; i++) {
		res *= i;
		res %= mod;
	}
	return res;
}
int mod_pow(int x, int y, int m = mod) {
	int res = 1;
	x %= m;
	while (y > 0) {
		if (y & 1) {
			res = res * x % m;
		}
		x = x * x % m;
		y >>= 1;
	}
	return res;
}
int comb(int x, int y) {
	if (y > x)
		return 0;
	return kai(x, y) * mod_pow(kai(y, y), mod - 2, mod) % mod ;
}
int get_rand(int MIN, int MAX) {
	std::random_device rnd;
	std::mt19937 mt32(rnd());
	std::uniform_int_distribution<int> engine(MIN, MAX);
	return engine(mt32);
}
struct BIT {
	vector<int> bit;
	int n;
	BIT(int x) {
		bit.resize(x + 1, 0);
		n = x;
	}
	void add(int x, int y) {
		while (x <= n) {
			bit[x] += y;
			x += x & -x;
		}
	}
	int sum(int x) {
		int res = 0;
		while (x > 0) {
			res += bit[x];
			x -= x & -x;
		}
		return res;
	}
};

struct UnionFind {
	vector<int> par, size;
	UnionFind(int x) {
		par.resize(x);
		size.resize(x, 1);
		rep(i,x)
			par[i] = i;
	}
	int find(int x) {
		if (par[x] == x)
			return x;
		return par[x] = find(par[x]);
	}
	bool same(int x, int y) {
		return find(x) == find(y);
	}
	int consize(int x) {
		return size[find(x)];
	}
	void unite(int x, int y) {
		x = find(x), y = find(y);
		if (x == y)
			return;
		if (size[x] < size[y]) {
			par[x] = y;
			size[y] += size[x];
		} else {
			par[y] = x;
			size[x] += size[y];
		}
	}
};

struct Tree {
	int size;
	vector<int> par, depth;
	vector<int> doubling[30];
	vector<vector<int>> G;
	int root = 0;
	Tree(int x) {
		par.resize(x);
		depth.resize(x);
		rep(i,30)
		{
			doubling[i].resize(x, -1);
		}
		G.resize(x);
		size = x;
	}
	void add_edge(int x, int y) {
		G[x].push_back(y);
		G[y].push_back(x);
	}
	void dfs(int x) {
		for (int i : G[x]) {
			if (depth[i] == -1) {
				depth[i] = depth[x] + 1;
				doubling[0][i] = x;
				dfs(i);
			}
		}
	}
	void init() {
		rep(i,size)
			depth[i] = -1;
		depth[root] = 0;
		dfs(root);
		rep(i,29)
		{
			rep(j,size)
			{
				if (doubling[i][j] == -1)
					doubling[i + 1][j] = -1;
				else
					doubling[i + 1][j] = doubling[i][doubling[i][j]];
			}
		}
	}
	int lca(int x, int y) {
		if (depth[x] > depth[y])
			swap(x, y);
		for (int i = 29; i >= 0; i--) {
			if ((depth[y] - depth[x]) >> i & 1) {
				y = doubling[i][y];
			}
		}
		if (x == y)
			return x;
		for (int i = 29; i >= 0; i--) {
			if (doubling[i][x] != doubling[i][y]) {
				x = doubling[i][x];
				y = doubling[i][y];
			}
		}
		return doubling[0][x];
	}
};

struct RollingHash {
	int Base = 283;
	const int MASK30 = (1ll << 30) - 1;
	const int MASK31 = (1ll << 31) - 1;
	const int MOD = (1ll << 61) - 1;
	vector<int> hash, power;
	int calcmod(int val) {
		val = (val & MOD) + (val >> 61);
		if (val > MOD)
			val -= MOD;
		return val;
	}
	int mul(int x, int y) {
		int xu = x >> 31;
		int xd = x & MASK31;
		int yu = y >> 31;
		int yd = y & MASK31;
		int mid = xd * yu + xu * yd;
		int midu = mid >> 30;
		int midd = mid & MASK30;
		return calcmod(xu * yu * 2 + midu + (midd << 31) + xd * yd);
	}
	RollingHash(string s) {
		//Base=get_rand(1<<7,1<<8);
		int sz = s.size();
		hash.resize(sz + 1, 0);
		power.resize(sz + 1, 1);
		rep(i,sz)
		{
			hash[i + 1] = (mul(hash[i], Base) + s[i]) % MOD;
			power[i + 1] = mul(power[i], Base) % MOD;
		}
	}
	int get(int l, int r) {
		int res = (hash[r] - mul(hash[l], power[r - l]) + MOD) % MOD;
		return res;
	}
	int lcp(int x, int y) {
		int len = min(hash.size() - y, hash.size() - x);
		int ok = 0, ng = len + 1;
		while (ng - ok > 1) {
			int mid = (ok + ng) / 2;
			if (get(x, x + mid) == get(y, y + mid))
				ok = mid;
			else
				ng = mid;
		}
		return ok;
	}
};
/*--------Library Zone!--------*/

int n,a[100005];
map<int,int>mp[100005],mp2[100005];
signed main() {
	cin>>n;
	rep(i,n)cin>>a[i];
	int ans=0;
	for(int i=n-2;i>0;i--){
		vector<int>v;
		for(int j=1;j*j<=(n-1-i);j++){
			if((n-1-i)%j)continue;
			v.push_back(j);
			if(j*j!=(n-1-i))v.push_back((n-1-i)/j);
		}
		for(int j:v){
			mp[i][j]=mp[i+j][j]+a[i];
		}
	}
	REP(i,n-1){
		vector<int>v;
		for(int j=1;j*j<=i;j++){
			if(i%j)continue;
			v.push_back(j);
			if(j*j!=i)v.push_back(i/j);
		}
		for(int j:v){
			mp2[i][j]=mp2[i-j][j]+a[i];
		}
	}
	REP(i,n-1){
		vector<int>v;
		for(int j=1;j*j<=(n-1-i);j++){
			if((n-1-i)%j)continue;
			v.push_back(j);
			if(j*j!=(n-1-i))v.push_back((n-1-i)/j);
		}
		for(int j:v){
			if(i<j)continue;
			int ko=(n-1-i)/j;
			if(i%j==0){
				if(ko*j>=i)continue;
			}
			int ans1=mp[i][j];
			int ans2=mp2[ko*j][j];
			chmax(ans,ans1+ans2);
		}
	}
	cout<<ans<<endl;
}


Measured memory_bytes: 172416