How would I create a formula to choose X number of unique cells from
an array? For example,

A1 = Bob
A2 = Mary
A3 = Bill
A4 = Tom
A5 = Dick


I need to choose at random, 3 of these names and they have to be
unique. On a larger scale, I have a database of 1500 names and I need
to select 50 unique names (cells) at random.

Thanks,
Brian