Could you check if my calculations are OK?

This is the function (check Pell numbers for more info):

public static final int F(int n) { if (n < 1) return 0; if (n == 1) return 1; else return 2*F(n-1)+F(n-2); }

My calculations were based on this PDF (first example). I assumed the recursive call makes 3 operations before calling the function again(*, -, +) and did my calculations here (MathBin latex page).

I've come to the conclusion the growth is exponential. If there's anything wrong or not understandable, please let me know.

Thank you very much,

Ted.