#include <stdio.h>
/* Define recursive_power_of_2 function: */
int recursive_power_of_2 (int n) {
  if (n == 0)
    return 1;
  else
    return 2 * recursive_power_of_2 (n - 1);
}
/* Test recursive_power_of_2 function in main: */
main ( ) {
  printf ("The 0th power of 2 is %i.\n", recursive_power_of_2 (0));
  printf ("The 1st power of 2 is %i.\n", recursive_power_of_2 (1));
  printf ("The 2nd power of 2 is %i.\n", recursive_power_of_2 (2));
  printf ("The 3rd power of 2 is %i.\n", recursive_power_of_2 (3));
}