Consider the function f0: [0,1) → R with a given formula

f0 (x) = x-12.

Let's specify fn+1(x)=fn({24x/13}), where {x}=x−⌊x⌋ is a fractional part of the number x. Let θn be the tangent of the largest acute angle that the graph of fn creates with the axis OX. Find ⌊θ13⌋.