http://cthbstalpha.blogspot.com/2016/05/ZJd881.html

ZJd881.cpp

/**********************************************************************************/
/*  Problem: d881 "作業苦多" from CSDC                                        */
/*  Language: CPP (334 Bytes)                                                     */
/*  Result: AC(4ms, 364KB) judge by this@ZeroJudge                                */
/*  Author: cthbst at 2012-02-05 20:04:16                                         */
/**********************************************************************************/


#include<iostream>


using namespace std;
int main (int argc,char*argv[])
{
    int in0 ;
    
    while (cin >>in0 ){
          int sum =2 ,ru =1 ;
          
          for (int i=1 ;i<50;i++){
              sum += ru, ru = 1+(2+i*in0)*(i+1)/2;
          }
          cout <<sum <<endl ;
    }
    
    return 0 ;
}