I have a table something like this:

A B
1234 1
1345 1
1345 2
1347 1
1355 1
1358 2
1366 1
1366 2
1375 1


Column A contains a variety of numbers which are usually unique, but sometimes duplicate.
Column B contains either a 1 or a 2.

My need is to count the number of times Column B = 2 AND the corresponding value for A is equal to the value for A of the previous row.

So for example, in the table above the first time B=2 is in B3. I then want the formula to slide over and compare to see if A3=A2 and if it does, to include B3 in the count.

I've been playing around with all sorts of strange formulas using COUNTIFS, OFFSET, MATCH, and others but I'm at a loss since I'm far from an excel guru.

Please help.

Thanks.