[seqfan] Re: sigma(n) =

[Chris Thompson]

On Nov 20 2015, M. F. Hasler wrote:

>On Fri, Nov 20, 2015 at 5:59 AM, Olivier Gerard
><olivier.gerard at gmail.com> wrote:
>> In my opinion,  the sequence 5)  sigma(n) = 2*sigma(n - 2)   is interesting
>> and you should submit it.
>>
>>
>> On Wed, Nov 11, 2015 at 8:07 AM, юрий герасимов <2stepan at rambler.ru> wrote:
>>> Dear SeqFans, also n such that:
>>>
>>> 5) sigma(n) = 2*sigma(n - 2): 120. 1560, 2940, 17760, 19920, 32220, 33840,
>>> 55965, 710040, 186780, 308040, 511500, 523776, 553500, 699360, 838215, ...
>
>Looking at the first terms, it seems that this is a subsequence of A204830.

Plausible for the even values, but there are odd values (e.g. 55965, 838215)
which have sigma(n) < 3*n and so are certainly not in A204830.

-- 
Chris Thompson
Email: cet1 at cam.ac.uk