Journal of Integer Sequences, Vol. 17 (2014), Article 14.9.2

On the Ratio of the Sum of Divisors and Euler's Totient Function II


Kevin A. Broughan and Qizhi Zhou
Department of Mathematics
University of Waikato
Private Bag 3105
Hamilton
New Zealand

Abstract:

We find the form of all solutions to φ(n) | σ(n) with three or fewer prime factors, except when the quotient is 4 and n is even.

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(Concerned with sequences A000010 A000043 A000203 A000668 A003307 A062699 A068390 A079363 A104901.)

Received October 31 2013; revised version received August 4 2014. Published in Journal of Integer Sequences, August 12 2014.

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