auto number with condition

[7ryota]

i am trying to automate the numbering with prefix (in column A) but with ifs condition in column K

i have column K with the selection of ("VMS", VMS_FP" and "Patch")

the condition as follows
if VMS, the next numbering should start with VA27
if VMS_FP, the next numbering should start with VA13FP
if Patch, the next numbering should start with PA28

the number should increase with the next selection of either VMS, VMS_FP or Patch

can i seek your highlighten on how should i derive on the formula

 

[Radoslaw Poprawski]

minisheet please with exaple of expected solutin and the data ur working with