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On the ratio of the sum of divisors and Euler’s Totient Function I

Abstract
We prove that the only solutions to the equation σ(n)=2φ(n) with at most three distinct prime factors are 3, 35 and 1045. Moreover, there exist at most a finite number of solutions to σ(n)=2φ(n) with Ω(n)≤ k, and there are at most 22k+k-k squarefree solutions to φ (n)|σ(n) if ω(n)=k. Lastly the number of solutions to φ(n)|φ(n) as x→∞ is O(x exp(-½√log x)).
Type
Journal Article
Type of thesis
Series
Citation
Broughtan, K. A. & Delbourgo, D. (2013). On the ratio of the sum of divisors and Euler’s Totient Function I. Journal of Integer Sequences, 16, article 13.8.8.
Date
2013
Publisher
Degree
Supervisors
Rights
This article has been published in the Journal of Integer Sequences. © 2013 the authors.