Identify 2 or 3 Conescutives in a string of data

Using the sample file:

F2:
=IF(OR($E2<>$E1,$F1=3),"",INDEX({"",2,3,""},MATCH(COUNTIF(INDEX($E:$E,MATCH(2,INDEX(1/($E$1:$E1<>$E2),0))+1):$E2,$E2),{0,2,3,4})))
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though I should add that I don't necessarily concur with your expected results... based on my understanding:

F10 should be 2 rather than F11
F14 should be 2 rather than F15
F36 should be 2 rather than Null

edit: I am sure with more thought the above can be simplified ... it's not efficient.

edit: in hindsight there's no need for the COUNTIF overhead given the same result can be achieved using just the use ROW difference

F2:
=IF(OR($E2<>$E1,$F1=3),"",INDEX({"",2,3,""},MATCH(ROW($F2)-MATCH(2,INDEX(1/($E$1:$E1<>$E2),0)),{0,2,3,4})))
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