Can you configure a LF Form to utilize dynamic fields in the following manner?

2 Fields:

ACCOUNT#

CARRIER (List field containing TRAIN, PLANE, TRUCK)

When TRAIN is selected within the form, I would like to dynamically assign field ACCOUNT# with the value 5000 (would like the next ACCOUNT# to increment one to 5001, etc)

When PLANE is selected within the form, I would like to dynamically assign field ACCOUNT# with the value 6000 (would like the next ACCOUNT# to increment one to 6001, etc)

When TRUCK is selected within the form, I would like to dynamically assign field ACCOUNT# with the value 7000 (would like the next ACCOUNT# to increment one to 7001, etc)

Thanks in advance.