How do I prevent duplicate numbers in a range of validated cells?
 

I have a validation rule for a series of cells. The 3 cells are only
allowed to have a value of 3, 5, or 1. I want to fix it so that each
number may only be used once in a range of 3 cells. .... So in A1:A3,
each number may only appear once or an error message pops up or the
cell starts blinking ~ something needs to happen to notify the user
that there is an error that needs correcting.


THanks