Topic: http: //codeforces.com/contest/268/problem/B
#include <iostream> using namespace std; int main() { int n; cin>>n; int ans=0; for(int i=1;i<n;i++) { ans+=i*(n-i); } ans+=n; cout<< ans; }
Reproduced in: https: //www.cnblogs.com/danielqiu/archive/2013/01/29/2882110.html