Suggestion for "more" page.

[David Wilson]

According to the format page:

hard: Next term is not known, and may be hard to find. Would someone please 
extend this sequence?

Even if we promise to avoid epistomological questions, there is much 
practical vagueness with this definition.  Known to whom?  Hard to find for 
whom?

Oftentimes, an author with generally limited mathematical skils and/or 
ignorance of a specific area of mathematics (e.g, Polya counting methods) 
will find a particular sequence hard to extend while another may find it 
easier.  An example is A018807.  Prior to my work on this sequence, a(4) = 
281571 was the largest value I was able to find in the literature.  I wrote 
a brute-force king-placing program that was able to compute a(5) = 32572756, 
a(6) would have taken weeks to compute by this method.  Finally I hit on a 
state-machine algorithm that allowed me to compute the remaining values you 
find on that sequence.  In theory, it could have computed several more 
terms, but space limititations on my machine caused thrashing that made 
computing the next term practically impossible.

The same technique could be applied to other sequences.  For example, I 
beleive there is a sequence that counts rook tours on a 4xn board which is 
labeled "hard".  The technique I used for A018807 could greatly extend this 
sequence, so in a computational sense it is "easy".  However, writing the 
algorithm is difficult (which is why I haven't attempted it), so in that 
sense the sequence is "hard".

----- Original Message ----- 
From: "Don Reble" <djr at nk.ca>
To: "Seqfan" <seqfan at ext.jussieu.fr>
Sent: Monday, August 08, 2005 12:19 AM
Subject: Re: Suggestion for "more" page.


>>> To this end, I propose that the "more" page classify "more" sequences
>>> according to whether the "hard" keyword also appears.
>
> I used to attack the more's. I often found that the "hard" flag was
> misused: some of those sequences were downright trivial. (So I flagged
> my extensions with "easy". Mysteriously, that seemed to cancel the
> "hard", and neither flag appeared in the final results. :-)
>
> I would have preferred a way to show the more's which weren't authored
> by a particular author, even when that author misspelled his name. But
> that's asking a lot.
>
> -- 
> Don Reble  djr at nk.ca