Preventing Duplicate Sequences

Rick Shepherd R.Shepherd at
Fri May 9 22:27:34 CEST 2003

Hello.  The subject is how to best *prevent* duplicate sequences -- or just
to increase awareness and suggest that this topic may belong in the OEIS
FAQ, perhaps as an extended answer to "What should I do before submitting
a new sequence?".

During about a week (while adding 49 other, related sequences)  I've
encountered 19 duplicate sequences in the OEIS -- 10 I've already reported
and 9 more I'm about to report.  (The latter set includes 3 sequences which
are identical!).  NJAS has already stated that he'll merge the first 10

There are many common-sense reasons why duplicates should be avoided -- not
the least of which is that they cost lots of people extra work (and/or
perhaps missed references if they find the "wrong" one first).

The big question is:  Should there be an automated check at the time we
submit new sequences to issue a warning (to the submitter and would-be
updater) if an identical sequence (or nearly so) is already in the database?
spite of best efforts to check manually beforehand there could always be
of two people sending in the same sequence at about the same time....

[Of course, it is reassuring when both sequences really are identical
(rather than accidentally differing in, say, one or two terms... :^j)  ).]

Rick Shepherd

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