[seqfan] Are sequences like A015762 finite?

Alonso Del Arte alonso.delarte at gmail.com
Mon Aug 21 17:44:16 CEST 2017


A015762 consists of numbers n such that phi(n) divides sigma_4(n). These
are the numbers listed:

1, 2, 3, 6, 249, 498

Harvey's 2012 Mathematica program only goes up to 500, but can easily be
changed to go much higher than that. I've taken it up to 10000 and found no
further terms.

Intuition is no substitute for proof, but no proof suggests itself to me at
the moment. My intuition tells me that this sequence is finite.

There are very similar sequences in its immediate neighborhood of A-numbers.

Al

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Alonso del Arte
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