Apex Jobs Cron jobs

<!-- Schedule MyBatchScheduler to run every 15 minutes -->
List<Integer> minutes = new List<Integer>{0, 15, 30, 45};

for (Integer i : minutes) {
    String cronExp = '0 ' + i + ' * * * ?';
    String jobName = 'MyBatchJob_' + i;
    System.schedule(jobName, cronExp, new MyBatchScheduler());
}