/* Sample Exercise 2
 
   A triangular number can also be generated by the formula
 
   Triangular number = n (n + 1) / 2
 
   for any integer value n.  Write a program to generate every
   fifth triangular number between 5 and 50 (5, 10, 15 ... 50)
*/
 
/* with a for loop */
#include <stdio.h>
main ()
{
 
   int n;         /* a number */
   int tri_num;   /* the triangular value of the number */
 
   printf ("TABLE OF TRIANGULAR NUMBERS by 5\n\n");
   printf (" n     Triangular Number\n");
   printf ("---    -----------------\n");
 
   tri_num = 0;
 
   for (n = 5; n <= 50; n = n + 5)  /* or n+= 5 */
   {
       tri_num = (n * (n + 1))/2;
       printf (" %d        %d\n", n, tri_num);
   }
   return (0);
}
 
 
/* with a do loop */
 
 

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