Player rating for tournaments across all installments of Heroes.

I calculated some coefficients here, and if someone can link them to a formula (I think it's possible), it would be great. Participants - Coefficient 10 - 0.631 15 - 0.736 20 - 0.795 25 - 0.832 30 - 0.858 It's a bit difficult for me to derive such a formula based on five data points.