Click here to download collatz.c.

#include <stdio.h>

int main() {
  int x;
  scanf(" %d", &x);
  while (x > 1) {
    if (x % 2 == 0) {
      x /= 2;
    }
    else {
      x = 3*x + 1;
    }
    printf("%d\n", x);
  }
  return 0;
}