series

#include<iostream.h>
#include<conio.h>
 void main()
 {
  int n, i, sum=0, j;
  clrscr();
  cout<<"1+2+4+7+11+16+--------+n"<<endl;
  cin>>n;
  j=1;
  for(i=0; i<=n; i=i+j)
  {
  sum=sum+i;
  j++;
  }
  cout<<"Total of the series="<<sum<<endl;
  getch();
 }