[seqfan] Re: Style sheet about offset

[Joerg Arndt]

OK, a simple sentence in the style sheet indicating "this has to do
with internal ordering" (or something like that) may save some
scratching of head.

Best regards,   jj


* Neil Sloane <njasloane at gmail.com> [Dec 31. 2018 09:13]:
> The answer is simple, and there is a very good reason.  The reason is a
> decision I made 50 years ago.
> 
> All the sequences are arranged lexicographically, but to do that they have
> to be lined up, and I decided to line them up so the first field they are
> sorted on is the first term >= 2 in magnitude
> 
> You can't compare the Fib numbers and the primes unless you line them up
> properly
> 
> 0 1 1 2 3 5 8 13 ...
> 2 3 5 7 11 13 ...
> 
> You mark the first term > 1 in magnitude with  asterisks (this is the
> second offset):
> 
> 0 1 1 *2* 3 5 8 13 ...   (second offset is 4)
> bbbbb*2* 3 5 7 11 13 ...  (b means a blank character) (second offset is 1)
> 
> and now can compare them .  They are out of order!  The correct order is
> 
> 
> bbbbb*2* 3 5 7 11 13 ...
> 0 1 1 *2* 3 5 8 13 ...
> 
> The primes come before the Fib numbers.
> 
> You can still see this arrangement today, look at the line in any entry
> that says
> "Sequence in context"  That shows you the three sequences before and after
> the one you are looking at, in the lex, order.
> 
> Let me give you an example, picked at random from a window I have open:
> 
> For A219585, the sequence is
> 1, 1, 1, 1, 1, 1, 1, *2*, 1, 1, 1, 5, 5, 2, 1, 1, 15, 40, 17, 2, 1, 1, 52,
> 457,
> which has offset line 0,8
> meaning that when we sort it we begin comparing at the 8th field, the 2
> that I marked with asterisks.  The OEIS entry has these two lines.  You can
> probably guess what the second line is.
> 
> 
> Sequence in context: A181783 <https://oeis.org/A181783> A121395
> <https://oeis.org/A121395> A275377 <https://oeis.org/A275377> * A292464
> <https://oeis.org/A292464> A090628 <https://oeis.org/A090628>A054387
> <https://oeis.org/A054387>
> 
> Adjacent sequences:  A219582 <https://oeis.org/A219582> A219583
> <https://oeis.org/A219583> A219584 <https://oeis.org/A219584> * A219586
> <https://oeis.org/A219586> A219587 <https://oeis.org/A219587>A219588
> <https://oeis.org/A219588>
> 
> 
> The first line tells you that sequences A275377 and A292464 are very close
> to that one in the ordering.
> 
> 
> OK, now to answer your question.  If all terms are less than 2 in
> magnitude, you can't sort them like this.  So those get sorted on the first
> field. Get it?  This makes perfect sense.
> 
> 
> I think you are confusing the first offset and the second offset.  Of
> course the first offset is meaningful for a 0 -1 +1 sequence.  But the
> second is not.
> 
> 
> 
> 
> Incidentally, there seems to be a bug in the system. For A79, powers of 2,
> those two lines are:
> 
> Sequence in context: A120617 <https://oeis.org/A120617> A131577
> <https://oeis.org/A131577> A155559 <https://oeis.org/A155559> A171449
> <https://oeis.org/A171449> A122803 <https://oeis.org/A122803> A274867
> <https://oeis.org/A274867> A274866 <https://oeis.org/A274866>
> 
> Adjacent sequences:  A000076 <https://oeis.org/A000076> A000077
> <https://oeis.org/A000077> A000078 <https://oeis.org/A000078> * A000080
> <https://oeis.org/A000080> A000081 <https://oeis.org/A000081>A000082
> <https://oeis.org/A000082>
> 
> 
> The asterisk is missing from the first line!   Russ?
> 
> 
> On Sun, Dec 30, 2018 at 8:49 AM Joerg Arndt <arndt at jjj.de> wrote:
> 
> > In   http://oeis.org/wiki/Style_Sheet#Offset
> > we say
> >   "There is a second part to the offset after a comma, which is the
> >    1-based index of the first term which is greater than 1 in absolute
> >    value."
> > So far, so good.  But then:
> >   "If all terms are -1, 0, or 1 the second part should be 1."
> > Why on earth is the counter-intuitive (and IMO plain illogical)
> > part there?
> >
> > Best regards,   jj
> >
> >
> > --
> > Seqfan Mailing list - http://list.seqfan.eu/
> >
> 
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