Multiply by 1.2 for 120%, .96 for 96%, or .02 for 2%, etc.

if(r == 1, 1.2, if(r == 2, .96, if(r == 3, .82, if(r == 4, .70, if(r == 5, .60, if(r == 6, .50, if(r == 7, .40, if(r == 8, .3, if(r == 9, .2, if(r == 10, .1, 0)))))))))) * 1500 + (if(n > 10, (n-10)*.02, 0) * 1500)

This formula is as close as I get get with your description. Note that it gives 2% of 1500 points for each player over 10 in the tournament. So, as in your example, if there are 14 players, it would give an additional 8% to _every_ player. To give that extra 8% to only the top 10 finishers, use this one:

if(r == 1, 1.2, if(r == 2, .96, if(r == 3, .82, if(r == 4, .70, if(r == 5, .60, if(r == 6, .50, if(r == 7, .40, if(r == 8, .3, if(r == 9, .2, if(r == 10, .1, 0)))))))))) * 1500 + if(r <= 10, (if(n > 10, (n-10)*.02, 0) * 1500), 0)

I'll break this down for you:

if(r == 1, 1.2, if(r == 2, .96, if(r == 3, .82, if(r == 4, .70, if(r == 5, .60, if(r == 6, .50, if(r == 7, .40, if(r == 8, .3, if(r == 9, .2, if(r == 10, .1, 0))))))))))

This computes the % that the player receives, based on their finishing rank. It checks specifically for ranks 1 through 10 and gives a unique percentage for each one, or 0 if the rank is not 1 through 10. We then multiply that by 1500 to get the actual points.

if(r <= 10, (if(n > 10, (n-10)*.02, 0) * 1500), 0)

This part adds additional points only if they ranked in the top 10. And the inner part of it:

(if(n > 10, (n-10)*.02, 0) * 1500)

... computes the additional percentage to add (number of players minus 10, multiplied by 2%), and multiplies it by 1500 to get the actual additional points.

Those two parts are added together for the final points.

Here's the first formula above run for a tournament with 14 players:

1st, 1,920.00

2nd, 1,560.00

3rd, 1,350.00

4th, 1,170.00

5th, 1,020.00

6th, 870.00

7th, 720.00

8th, 570.00

9th, 420.00

10th, 270.00

11th, 120.00

12th, 120.00

13th, 120.00

14th, 120.00

And here's the second one run for a tournament with 14 players:

1st, 1,920.00

2nd, 1,560.00

3rd, 1,350.00

4th, 1,170.00

5th, 1,020.00

6th, 870.00

7th, 720.00

8th, 570.00

9th, 420.00

10th, 270.00

11th, 0.00

12th, 0.00

13th, 0.00

14th, 0.00