[seqfan] Re: Number of solutions of sigma(x) = n.

Allan Wechsler acwacw at gmail.com
Wed May 14 16:45:11 CEST 2014


[facepalms] Thank you for finding my error. The five-digit sequence number
confirms my intuition that this was too good to be true.


On Wed, May 14, 2014 at 2:28 AM, Charles Greathouse <
charles.greathouse at case.edu> wrote:

> This is A054973; sigma(6) = 12, not 6. (And I don't think we're ready for
> A250000 yet.)
>
> Charles Greathouse
> Analyst/Programmer
> Case Western Reserve University
>
>
> On Tue, May 13, 2014 at 4:04 PM, Allan Wechsler <acwacw at gmail.com> wrote:
>
> > If I have done this right, the first few entries are 1, 0, 1, 1, 0, 2, 1,
> > 1, 0, 0. For example, a(6) = 2 because sigma(5) = sigma(6) = 6, and
> a(24) =
> > 3 because sigma(14) = sigma(15) = sigma(23) = 24.
> >
> > If my paper calculations were right for the first few entries, I am
> really
> > surprised to find this missing from OEIS, and am inclined to nominate it
> > for sequence A250000. It has many links with existing sequences relating
> to
> > sums of divisors.
> >
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> >
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> >
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