Certain ergodic, piecewise
Möbius self-mappings of the unit interval, similar to the classical Gauss or Rényi
maps, give rise to natural sequences of convergents pn∕qn for every associated
“irrational” number x. Here we study the metric theory of the approximation
sequences 𝜃n= |qn||qnx − pn|. Following Jager we describe the distribution of pairs
(𝜃n,𝜃n+1) in a plane domain by deriving their distribution function. As a
consequence we get a generalization of the theorem of Bosma, Jager and Wiedijk,
referred to as the Lenstra Conjecture, which describes the distribution of the
𝜃n.