Obscure notation. what I wanted is:
t_internet - t_arpanet = 2^p
t_history - t_gutenberg = 5^p
where t_internet is in the range [t_arpanet, 210] (in decades) and t_history is in the range [t_gutenberg, t_arpanet] (in decades).
Therefore, if a historic event related to the printing press occured at t_history time (in decades) then the equivalent event related to the net occured at t_internet (in decades), given by te formula:
t_internet = t_arpanet + (t_history - t_gutenberg)^0,43067
where 0,43067 = (ln 2)/(ln 5).