#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>


int main(int argc, char **argv) {
    if (argc != 2) {
        fprintf(stderr, "Usage: forkloop <iterations>\n");
        exit(1);
    }

    int iterations = strtol(argv[1], NULL, 10);

    for (int i = 0; i < iterations; i++) {

        if(i == 0){
            int n = fork();

            if (n < 0) {
                perror("fork");
                exit(1);
            }
        }

        printf("ppid = %d, pid = %d, i = %d\n", getppid(), getpid(), i);
    }

    return 0;
}

the new children do not create additional processes.  Only the original parent calls fork. Keep the printf call for all processes.