Formula to Sequnce Numbers from the Max number present in the column based on rules

Looking for a complex formula or a VBA script to create for the data below:

jobid  dep  job_no   Sequence   
 aaa   FJ     1         1        (existing data)
 aaa   FJ     1         2
 aaa   FJ     1         5
 aaa   RJ     1         1
 aaa   FJ     2         1
 aaa   FJ     2         2
 aaa   FJ     2         4
 aaa   FJ     2         5
 ccc   RJ     1         1
 ccc   FJ     2         1
 aaa   FJ     1         6       (newly added data)
 aaa   FJ     1         7
 ccc   FJ     2         2

Need the sequence column to auto populate or something similar.

So basically there will already exist a table as above, but what the formula should do is continue the count from the last max count irrespective of a deleted number in between for the newly added data when the columns are matched.

Any solution will be appreciated.