  Using a generalized function of the stellar spin-down law, we investigate the
age dependence of the magnetic braking index ($q$). Our survey includes 9 open
clusters aged lower than 1 Gyr and ranged in mass from 0.7 to 1.1$M_{\odot}$.
Our aim is to verify the time behavior of the nonextensive braking index $q$
which brings the cumulative distribution of the rotational velocities of the
stars of the youngest cluster ($\alpha{\rm Per}$) taken at the future age of an
older cluster. As a result, the $q$-index is calculated over time
$t-t_{\alpha{\rm Per}}$, where $t$ is the age of older open cluster used to
estimate the future cumulative distribution of the rotational velocity of the
$\alpha{\rm Per}$ cluster with present-day age $t_{\alpha{\rm Per}}$. We find
that the values of $q$ are slightly constant around 1.36 and 1.38 according to
the mass bin. In conclusion, the results seem to indicate that the mechanism
that controls the rotational decay of stars in open clusters does not depend on
the increment of time.
