Bug: 0 17 1 1/3 * isn't valid

[lakridserne]

This library says the expression 0 17 1 1/3 * isn't valid. But it is a valid cron expression. Can you please fix?

[dragonmantank]

This is indeed an invalid expression. You are month range of 1/3, which evaluates to Months 1, stepping by 3 values. Since the range is effectively 1 month, it's impossible to skip any further.

If you want to run something every three months, you would need to use */3 instead. That evaluates to `Months 1-12, stepping by 3 values.