Unique Values In A List That Appear At Least 3 Times (2007)

=COUNT(

1/FREQUENCY(

MATCH($A$1:$A$50,$A$1:$A$50,0)

),

ROW($A$1:$A$50)-ROW(OFFSET($A$1:$A$50,0,0,1,1))

+1))

I'm looking to tweak this formula to count the number of unique values that occur at least 3 times.

So, imagine that A1:A50 contain 50 last names from the phone book, 27 of which are unique according to the formula above.

Now, further imagine that only 5 of these unique 27 last names appear at least 3 times.

I'm looking for the formula that returns 5.

And (like always), for simplicity and sharing reasons, I'm hoping to find a single formula that occupies a single cell, and does not rely on additional columns of intermediate information.