The Lyapunov exponent for logistic map $x_{n+1}=f(x_n) $ where f is given by $f(x)=bx(1-x)$ is given by: $$\lambda = \frac{1}{n}\sum^n_i log(b(1-2x_i))$$ where the index $i$ refers to $i$th iterate
http://demonstrations.wolfram.com/LyapunovExponentsForTheLogisticMap/
I read that $\lambda$ is constant for a fixed value of $b$. I want to ask why does it not depend on the seed value say $x_1$, since for any value of $b$, I can start with any value of $x_1$ between 0 and 1?