[seqfan] Re: Consecutive sigmas

[Emmanuel Vantieghem]

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