I think Magic_fubu is right. Well, maybe you can do this. You'd have to award the points using the Overall Score formula on the Stats profile.
So you would leave your Points for Playing as Magic_fubu showed:
(n-r+1)*2+switch(r,1,8,2,6,3,4,4,2,0)
In the Stats Profile (or Stats Filter, if you're using version 2), set your Tournament Scores formula to:
points
and set your Overall Scores formula (one of them) to:
sum(scores) + max(0, (count(scores) - 5) * 2)
This sets the score value for each player, for each tournament, equal to the number of points the player earned for that tournament. Then, the Overall Score sums up the scores (points). The scores already include 1 point for each tournament the player participated in. The Overall Score formula adds 2 points for each tournament over 5 that the player has participated in, bringing it up to 3 points for each tournament over 5.
So the player's Points listing on the Points tab would be the points earned for the current tournament, and would only reflect the 1 point for playing. It would not know if the player had played in 1, 2, 5, or 10 tournaments, so it cannot award additional once they've played in 6 tournaments. But when you run Stats, the Overall Score should reflect the player's total points for all tournaments, including the 2 additional points for each tournament over 5.