#include<bits/stdc++.h>
#define mod 1000000007
using namespace std;
unsigned long long n,a[5010],m,ans;
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>m;
		a[m]++;
	}
	for(int i=1;i<=5000;i++){
		if(a[i]>1){
			for(int j=1;j<=i/2;j++){
				if(j==i-j&&a[j]>0&&a[i-j]>0)ans=(ans+((a[j]*(a[j]-1)/2)%mod)*(a[i]*(a[i]-1)/2)%mod)%mod;
				if(j=i-j&&a[j]>1)ans=(ans+((a[j]*a[i-j])/2%mod)*(a[i]*(a[i]-1)/2)%mod)%mod;
			}
		}
	}
	cout<<ans%mod;
}