[seqfan] Re: List the dividers, sum the digits

[Robert Gerbicz]

Sum of the digits of all divisors of n is less than
t(n)=(2*sqrt(n)+1)*9*(log(n)/log(10)+1), but for t>10000 t(n)<n, and up to
n=10000 there is no more cycle, this gives that there is no other cycle.

2015-11-08 1:03 GMT+01:00 Hans Havermann <gladhobo at teksavvy.com>:

> > Example for A=10:
> > 10--> 1,10,2,5 dig.sum=9
> > 9--> 1,9,3      dig.sum=13
> > 13--> 1,13       dig.sum=14
>
> I think the dig.sum=5 on that last one but it does indeed end at 15:
>
> 10, 9, 13, 5, 6, 12, 19, 11, 3, 4, 7, 8, 15.
>
> Is there any sink other than 15 for starting numbers > 1 ?
>
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