int s = 1;
int n;
for (n = 1; n <= 5; n++)
{  
   s = s + n;
   cout << s << " ";
}

prints 2 4 7 11 16

int s = 1;
int n;
for (n = 1; n <= 5; cout << s << " ")
{  
   n = n + 2;
   s = s + n;
}

prints 4 9 16

int s = 1;
int n;
for (n = 1; n <= 5; n++)
{  s = s + n;
   n++;
}
cout << s << " " << n;

prints 10 7