Comparing Activitiy Sequences

Hi. I’m trying to find a way to compare the number of times that a certain activity sequence occurs as an “Update” to the first “Initial” activity sequence.

Example:
INVK and INTA are processing status settings. In the first sequence of INVK to INTA, both activities have a change indicator “I” (Initial). If the sequence occurs again, both activities have a change indicator “U” (Update). Any subsequent occurrences of this sequence will also have the change indicator “U”.

Problem:
I need to count the specific activity sequences (i.e. INVK to INTA), not just the number of cases in which the sequence occurs and also not just the number of times each activity occurs (e.g. either the number of times that INVK or INTA occurs). For example, if a certain case passes through the INVK-INTA sequence 3 times, I should get a result of 2 “Updates” to 1 “Initial” for the case.
I’ve tried using various Match Activity formulas but haven’t been able to get the correct results, so I would be greatful for any suggestions that could help.