[seqfan] Re: seqs whose |differences| are 1,2,3,4,...

Robert Munafo mrob27 at gmail.com
Fri Mar 12 03:04:10 CET 2010

All right, so there was confusion in two respects, or possibly three.

First the ambiguity in whether to start with 1,3,6,2,7,... or 2,4,7,3,8,...
Most of this thread was based on the former. Note that Paul Raff seems to
have gotten that guess right, i.e. he agrees with NJAS. In the existing
related work in OEIS (I count A005132, A064387-A064389, A113880,
A118201, A063733 and A078943) most start with (0,)1,3,6,2,7,... and there
are only two others, one of which starts with 1,1 which disqualifies it
right away.

There was a lot of effort to try to preserve both attributes "rearrangement
of the natural numbers" (implying bijection) and "lexicographically
earliest". Still some confusion there I think, having to do with how the
definitions are worded.

Also a little difficulty in understanding each other's discussions of the
algorithms (which is why I decided to pretty much figure it all out from

On Thu, Mar 11, 2010 at 18:19, N. J. A. Sloane <njas at research.att.com>wrote:

> > NJAS's initial statement referred to "natural numbers"
> To me the natural numbers are 1,2,3,4,5,...
> The nonnegative integers are  0,1,2,3,4,5,...
>  Best regards
>                         Neil

 Robert Munafo  --  mrob.com

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