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The \(3n+1\)-problem and holomorphic dynamics. (English) Zbl 1012.37028

Summary: The \(3n+1\)-problem is the following iterative procedure on the positive integers: the integer \(n\) maps to \(n/2\) or \(3n+1\), depending on whether \(n\) is even or odd. It is conjectured that every positive integer will be eventually periodic, and the cycle it falls onto is \(1\mapsto 4\mapsto 2\mapsto 1\). We construct entire holomorphic functions that realize the same dynamics on the integers and for which all the integers are in the Fatou set. We show that no integer is in a Baker domain (domain at infinity). We conclude that any integer that is not eventually periodic must be in a wandering domain.

MSC:

37F10 Dynamics of complex polynomials, rational maps, entire and meromorphic functions; Fatou and Julia sets
11B83 Special sequences and polynomials
37F50 Small divisors, rotation domains and linearization in holomorphic dynamics

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