#include<bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
    freopen("TricountUVa.in","r",stdin);
    freopen("TricountUVa.out","w",stdout);
    int n;
    while(1){
        cin>>n;
        if(n<3)break;
        int ans=0;
        for(int i = 1;i<=n;i++){
            if(i*2<n){
                ans+=(1+i-1)*(i-1)/2;
                ans+=(i-1)*(n-i*2);
            }
            else{
                ans+=(1+n-i-1)*(n-i-1)/2;
                
            }
            
            
//            for(int j = i+2;j<=n;j++){
//                ans+=j-1-max(j-i,i);
//            }
        }
        cout<<ans<<endl;
    }
    
    return 0;
}