[seqfan] Re: Don't forget the Index to the OEIS

Antti Karttunen antti.karttunen at gmail.com
Sat May 9 10:30:46 CEST 2020

On 5/9/20, Neil Sloane <njasloane at gmail.com> wrote:
> Dear Seq Fans, we accept about 1000 new sequences each month, often more.
> But no one ever remembers to update the Index!  Even I do not do that.

To make it easier for ones who update the Index, we can all try to
remember to add any appropriate index-links (those that have their own
"anchor") to the Links-section of the sequences we either edit or
submit. Also, if one is reviewing a submission by another person, then
I think one may well add any obviously appropriate links to the Index.

For example, here are a few that I have sometimes used:

<a href="/index/3#3x1">Index entries for sequences related to 3x+1 (or
Collatz) problem</a>
<a href="/index/Per#IntegerPermutation">Index entries for sequences
that are permutations of the natural numbers</a>
<a href="/index/Bi#binary">Index entries for sequences related to
binary expansion of n</a>
<a href="/index/Ce#cell">Index entries for sequences related to
cellular automata</a>
<a href="/index/Ch#char_fns">Index entries for characteristic functions</a>
<a href="/index/Ge#GF2X">Index entries for sequences related to
polynomials in ring GF(2)[X)</a>
<a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
<a href="/index/Su#sums_of_divisors">Index entries for sequences
related to sums of divisors</a>
<a href="/index/Mat#matula">Index entries for sequences related to
Matula-Goebel numbers</a>
<a href="/index/Pri#prime_indices">Index entries for sequences
computed from indices in prime factorization</a>
<a href="/index/Pri#primorial_numbers">Index entries for sequences
related to primorial numbers</a>
<a href="/index/Pri#primorialbase">Index entries for sequences related
to primorial base</a>
<a href="/index/Fa#facbase">Index entries for sequences related to
factorial base representation</a>
<a href="/index/Eu#epf">Index entries for sequences computed from
exponents in factorization of n</a>
<a href="/index/Ed#EKG">Index entries for sequences related to EKG sequence</a>
<a href="/index/St#Stern">Index entries for sequences related to
Stern's sequences</a>
<a href="/index/O#opnseqs">Index entries for sequences where odd
perfect numbers must occur, if they exist at all</a>
<a href="/index/Se#sequences_which_agree_for_a_long_time">Index
entries for sequences which agree for a long time but are
etc, etc.

Of course I don't always know or remember that there such an
index-entry exists for a given sequence. But in any case, when such
links are present, then updating the Index is much easier, as one can
just search from main OEIS search-field with keywords like "link:3x1"
"author:2019|author:2020" to find if there are any new Collatz-related
sequences submitted since Jan 1 2019, and update them "in batch mode"
to the Index. Provided of course that people remember to add such
index links.

Still one big missing thing from the Index is the "hover over" display
of titles we have on main OEIS site. Meanwhile, we could try to make
the Index more user-friendly than just throwing a lots of opaque
A-numbers into a big heap. E.g., when I created the index entry for
"Factorial base representation" (
https://oeis.org/wiki/Index_to_OEIS:_Section_Fa#facbase )
I tried to make it as clear as possible, separating sequences where
a(n) is a function of the factorial base representation of n, from
those that list particular terms whose factorial base representation
satisfies a certain pattern.

Maybe the decimal expansion related sequences could be similarly
reorganized and extended? (will be big!):
But I leave it for decimal base fans, as I am not expert in that field.

Best regards,


> The index is https://oeis.org/wiki/Index
> <https://oeis.org/wiki/Index_to_OEIS:_Section_De> and there is a link to it
> at the bottom of every OEIS page.
> (Remember that in order  to edit the Index, you need to login separately to
> the wiki.  And if you are a recent contributor, you might need to ask
> admin at oeis.org to give you permission to edit the wiki. )
> If someone were to ask me about improvements that are needed to the OEIS, I
> would say, *the Index needs a lot of work.*
> It is very hard to find sequences that are related to the one you are
> looking at.
> You can look at the CROSSREFERENCES, and you can click the "refs" tab (VERY
> But if the Index were more complete, it would be easier.
> The moral of this story is:
> if you happen to be studying sequences about a particular subject, look at
> the Index, and improve how this subject is covered in the Index.
> If you are thinking about sequences related to Recaman's Sequence, for
> example,  make sure that all the related sequences you find are mentioned
> in the Index under Recaman
> And if you submit a new sequence  related to XXX, mention it  (once it is
> accepted) in the Index under the XXX entry.
> .
> --
> Seqfan Mailing list - http://list.seqfan.eu/

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