Bill.com check numbers are sequenced across ALL Bill.com payments, rather than within a given account. As a result, your checks will not be cut in sequential order.
Create a "Bill Payments" report that lists all bill payments, including check payments and check numbers, from the Reports tab. Any other review of Bill.com payments could be performed using the Bill.com Payments Tab that lists a complete payment history.
Bank reconciliation should be easy -- Bill.com will make a single debit of your bank account for all payments processed on a particular day. Checks are then cut on our Bill.com bank account, and so the check numbers do not have to be matched back to your own bank account.