[seqfan] Re: easy and bref

Joseph S. Myers jsm at polyomino.org.uk
Fri Sep 30 01:38:40 CEST 2011

On Mon, 26 Sep 2011, Nathaniel Johnston wrote:

> Dear SeqFans,
> Another keyword combination that is quite ugly to my eye is "easy" and
> "more". I've cleaned up quite a few of these by adding more terms, but there
> are still 291 remaining. Most of these sequences still contain both keywords
> for one of two reasons: either the sequence is difficult to understand
> and/or needs editing by someone with expertise in the area (such as
> A002875), or it is "easy" to construct small terms by hand but writing a
> program to compute terms seems to be a nontrivial task (such as A072149).

I've submitted extensions and b-files for A072149-A072151 - they aren't 
that hard to program; A072152-A072154 to follow later.  I haven't tried to 
determine their generating functions, though they will certainly have 
rational generating functions.

There are 238 easy+more sequences left - I think most are probably 
genuinely easy once you've understood them (which is the nontrivial part 
in many cases).  Some look "easy" to add a few more terms to but not to 
extend to the full three rows let alone to 1000 terms in a b-file 
(A092645, for example).  It might be interesting to see what "easy" 
sequences there are that are significantly short of the normal three rows 
of numbers but aren't marked "more" (more generally, if a sequence is well 
short of three rows of numbers but isn't "full", it's a candidate for 
"more" unless it's known the next number would take it over three rows).

Joseph S. Myers
jsm at polyomino.org.uk

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