Auto sequential numbering within different series is truthfully a bit of a pain to set up.
My first suggestion is to challenge if there is a valid business reason to want them to be sequential within each series. Or is this just "how we always used to do it manually"
If you simply want them to start at different numbers for each Tyoe, then add say 60,000 to the Record ID if type A, and 90,000 to the Record ID if Type B.
If no one else takes the time to explain how to do sequential numbering within each series and you would like help setting this up, contact me at QuickBaseCoach.com