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From: Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups: comp.lang.c
Subject: Re: Suggested method for returning a string from a C program?
Date: Thu, 20 Mar 2025 12:14:49 -0700
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Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
> Michael S <already5chosen@yahoo.com> writes:
>> On Tue, 18 Mar 2025 21:38:55 -0400
>> DFS <nospam@dfs.com> wrote:
>>> I'm doing these algorithm problems at
>>> https://cses.fi/problemset/list/
>>>
>>> For instance:  Weird Algorithm
>>> https://cses.fi/problemset/task/1068
>>
>> It is not an interesting programming exercise.  But it looks to me as a
>> challenging math exercise.  I mean, how could we give a not too
>> pessimistic estimate for upper bound of length of the sequence that
>> starts at given n without running a full sequence?  Or estimate for
>> maximal value in the sequence?
>> So far, I found no answers.
>
> You may console yourself with the knowledge that no one else
> has either, even some of the most brilliant mathematicians
> of the last hundred years.  In fact it isn't even known that
> all starting points eventually terminate;  as far as what has
> been proven goes, some starting points might just keep going
> up forever.

I think someone has mentioned that this is called the Collatz
Conjecture.  According to Wikipedia, it's been shown to hold for all
positive integers up to 2.95e20 (which is just under 2**68).

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */