[seqfan] Re: easy and bref

Charles Greathouse charles.greathouse at case.edu
Fri Sep 30 19:22:15 CEST 2011


That's a non-example; I can think of many.  But what would an example be?

Charles Greathouse
Analyst/Programmer
Case Western Reserve University

On Fri, Sep 30, 2011 at 1:07 PM,  <franktaw at netscape.net> wrote:
> Well, consider A000043: Mersenne primes (p with 2^p-1 prime).
>
> Currently, we don't know any very efficient way of calculating these.
> (Better than primality testing for other numbers of the magnitude 2^p, but
> still very expensive as a function of p.) However, no one has proved that
> there isn't an efficient way to compute these. (The list might even be
> finite, in which case there is a very efficient calculation.)
>
> Franklin T. Adams-Watters
>
> -----Original Message-----
> From: Charles Greathouse <charles.greathouse at case.edu>
>
>> Interesting. My understanding of "hard" was just the opposite: that it
>> should be used when it is known that calculating more terms is hard,
>
> but not
>>
>> when there might be an easier way to make the calculation, but none
>
> such is
>>
>> known.
>
> I'm not sure when that would ever apply.  Would you give some examples?
>
> Charles Greathouse
> Analyst/Programmer
> Case Western Reserve University
>
>
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