Generating Sequential Numbers on Separate Forms

[GBays1]

I am creating a form in Info Path for customers to report problems with
equipment and each form needs to have a unique, preferably sequentially
ordered, number that is not repeated. The number range would be six
digits from 000001 - 999999. How do I create a formula, command...
whatever, that automatically inputs a sequentially ordered number onto
the form? This form will be online and available for printing. (not
sure if that makes a difference.)

GBays