Sequences with both "hard" and "more"

[Joseph S. Myers]

The keyword "hard" is defined as

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

and "more" is defined as

     * more: More terms are needed and should not be difficult to find.
       Would someone please extend this sequence?

Lots of sequences have both keywords.  The definitions don't literally
contradict each other, but the combination suggests a lot of uncertainty
about how hard the extension is, and why say "hard" if you think it
shouldn't be hard but just "may" be?

I think there are actually three different cases where extensions are 
wanted:

* "hard" for genuinely hard sequences, where an extension is wanted and
hard to find and should be added even if it takes the sequence over the
normal length limit.

* "more" for short sequences that should be easy to extend (but don't need 
extending beyond the normal limit).

* Automatic detection of sequences significantly below the length limit
that should be extended and haven't had a considered judgement on how hard
they would be to extend.  Without a human judgement on the difficulty,
there's no need for a keyword, as the length present is easy for a
computer to measure.

(So the list of sequences that need extending would be split into the 
different types.)

-- 
Joseph S. Myers
jsm at polyomino.org.uk