Average cells that contain numbers ignoring duplicates

If you want to average three numbers, but if two are the same only average two of the numbers you could use the following where Rge is a three cell range. "=AVERAGE(IF(SUM(COUNTIF(Rge,Rge)) = 3,Rge,IF(COUNTIF(Rge,Rge)>1.Rge,""))).
This formula counts the number of cells in the discontinuous range that contains a value greater than 20 "=INDEX(FREQUENCY((A1,A3,A5),20),2)".