5 color balls

There are five color balls in this game. When more than 5 balls with same color are in the same line together, the user gets scores. If only 5 balls in a line together, you get 5 scores. If more than 5 balls with same color are in a line (horizontal or vertical or diagonal), then scores that you get will be much more. For example,
5 balls --> 5
6 balls --> 5 + (6-5)*2
7 balls --> 5 + (6-5)*2 + (7-5)*2
8 balls --> 5 + (6-5)*2 + (7-5)*2 + (8-5)*2
n balls --> 5 + (6-5)*2 + (7-5)*5 + ... + (n-5)*2
Have fun.