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

Richard Mathar mathar at strw.leidenuniv.nl
Wed Feb 17 18:06:29 CET 2010

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

The in-degrees of the nodes illustrate http://www.oeis.org/classic/A054973 .


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