[seqfan] Re: Three lines, or 260 characters?

Simon Plouffe simon.plouffe at gmail.com
Tue Jul 3 04:17:00 CEST 2012

Hello seqfans,

  I have a collection of b-files that I made.

  In all, there are 2.1 billion terms and about 600 gigabytes
of data.

The format I have chosen is
A000009 0 1
A000009 1 1
A000009 2 1
A000009 3 2
A000009 4 2
A000009 5 3
A000009 6 4
A000009 7 5
A000009 8 6
A000009 9 8
A000009 10 10
A000009 11 12
A000009 12 15
A000009 13 18
A000009 14 22
A000009 15 27
A000009 16 32

I know that it does not resemble the format of the OEIS,
I made that for my own usage, it takes a lot of disk space
but for this I really don't care about that since I have 23 TB
of it. The most important thing is that I can access any term
and sequence within maple and make some programs to test some
hypothesis about numbers. That format and database is way too
big to be on the OEIS database and I can understand that this
format is not the most appropriate for distribution.

All of the sequences is referenced, if the formula is known
or can be computed then it is included in the database,
I took a copy of the existing ones and when it is possible
I extended those ones to 10000 terms or when the width is
lower that 4 K for each term when possible. The delicate
operation in all this was to properly put the initial term
in each sequence : the index (see column #2), so I applied
a series of filters to put all of this in place.
I understand that this process may not be the safest way to
process all the sequences but it is the way that I have found
that works with simple Unix scripts, maple and Mathematica.
  I have chosen that format because : each line is referenced,
one some occasions there are a lot of overhead data like
one file containing the first 100 million digits of pi
and some other known constants, it takes a lot of space but
at least I can access any sequence and term. On some others
like A000041 I have 10 million terms which were computed by
Alex (?),

  At one point, in December 2011, all of this data was on
my web site at www.plouffe.fr but the only clients I had
were those robots from Google and yahoo, microsoft, and most
importantly in some way it does infringe the OEIS policy on
copyright, this is were I decided to keep it on my home computer.

best regards,
  Simon plouffe

More information about the SeqFan mailing list