[seqfan] Re: Consecutive sigmas

Hugo Pfoertner yae9911 at gmail.com
Mon Mar 12 21:13:28 CET 2018


See https://oeis.org/draft/A300779 and https://oeis.org/draft/A300780 for
proposed new sequences.

On Mon, Mar 12, 2018 at 7:30 PM, Emmanuel Vantieghem <
emmanuelvantieghem at gmail.com> wrote:

> 2018-03-12 14:40 GMT+01:00 Hugo Pfoertner <yae9911 at gmail.com>:
>
> > The only 4 consecutive values in A002191 I could find are 12, 13, 14, 15
> at
> > the very beginning. Checking through m=10^7 there are two more
> occurrences
> > of consecutive odd sums sigma(m) of divisors:
> > sigma(36)=91, sigma(50)=93, but 92 doesn't occur as sigma.
> > and
> > sigma(241081)=241573, sigma(117128)=241575, 241574 again not in A000203.
> >
> > Might be interesting if we can find another occurrence of two consecutive
> > odd sigmas.
> >
>
>
> > There is one more occurrence of consecutive odd values of sigma below
> 10^8
> > :
>
> 38152387 = sigma(15069924), 38152389 = sigma(23011209) ;
> the number between them is not a sigma value.
>
> Emmanuel Vantieghem
>
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>


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