Calculating the Product of Odd Integers C++

#include<iostream>
#include<conio.h>
using namespace std;

main()
{
      
 int a=1,b=15,n;

 for(a=a;a<=b;a+=2)
 {
     cout<<a;
          if(a<b)
          {
              cout<<"+";
          }
 }

cout<<"=";
n=(b+1)/2;
n=n*n;
cout<<n;

getch();
}