[seqfan] Re: Mystery tour with a(n)=sigma(a(n-1))

Richard Guy rkg at cpsc.ucalgary.ca
Wed Feb 17 18:26:33 CET 2010

I haven't tried to look at this, but it
prompts the question as to whether there
is anything similar for the what-to-me-wd-be-
more-interesting analog for aliquot sequences:

              n --> sigma(n) - n

Is there such?     R.

On Wed, 17 Feb 2010, Richard Mathar wrote:

> A bystander's comment on
> http://list.seqfan.eu/pipermail/seqfan/2010-February/003687.html :
> One can draw a type of sociology diagram of which numbers
> join under the map  n->sigma(n) after some time.
> An example, showing only the fragments involving the first
> few hundred numbers, is displayed in the PostScript file
> http://www.strw.leidenuniv.nl/~mathar/progs/nTosigmaofn.ps .
> (This does not tell us anything beyond what was already
> posted...)
> The in-degrees of the nodes illustrate http://www.oeis.org/classic/A054973 .
> Richard
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