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Prime factors of dynamical sequences

  • Xander Faber EMAIL logo and Andrew Granville
Published/Copyright: December 1, 2011
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Journal für die reine und angewandte Mathematik
From the journal Volume 2011 Issue 661

Abstract

Let (t) (t) have degree d 2. For a given rational number x0, define xn1(xn) for each n 0. If this sequence is not eventually periodic, and if does not lie in one of two explicitly determined affine conjugacy classes of rational functions, then xn1xn has a primitive prime factor in its numerator for all sufficiently large n. The same result holds for the exceptional maps provided that one looks for primitive prime factors in the denominator of xn1xn. Hence the result for each rational function of degree at least 2 implies (a new proof) that there are infinitely many primes. The question of primitive prime factors of xnxn is also discussed for uniformly bounded.

Received: 2009-10-21
Revised: 2010-07-18
Published Online: 2011-December
Published in Print: 2011-December

Walter de Gruyter Berlin New York 2011

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