# [seqfan] Re: Numbers whose number of d's in base b is q.

Neil Sloane njasloane at gmail.com
Fri Apr 23 06:13:07 CEST 2021

```In that situation what we do is create an entry in  the Index to the OEIS,
and then just put a link to the index entry in every one of the sequences

For example, many sequences contain the link

Index entries for sequences related to cellular automata
<https://oeis.org/index/Ce#cell>

(see for example A070950) and the links point to a long entry in the Index

Best regards
Neil

Neil J. A. Sloane, President, OEIS Foundation.
11 South Adelaide Avenue, Highland Park, NJ 08904, USA.
Also Visiting Scientist, Math. Dept., Rutgers University, Piscataway, NJ.
Email: njasloane at gmail.com

On Thu, Apr 22, 2021 at 9:51 PM David Corneth <davidacorneth at gmail.com>
wrote:

> OEIS has a lot of sequences of the form
> Numbers whose number of d's in base b is q.
> For example there is
> Numbers whose number of 0's in base 5 is 1 (or some rewording of that)
>
> I figured how many of those are there so I started listing the numbers for
> each base and digits.
> Like
> A023729 [5, 2, 0] List([1, 3, 4, 5, 6, 8, 9, 15, 16, 18, 19, 20, 21, 23,
> 24, 25, 26, 28, 29, 30, 31, 33, 34, 40, 41, 43, 44, 45, 46, 48])
> That is the sequence
>   A023729 is  Numbers whose number of 2's in base 5 is 0. (but actually
> Numbers with no 2's in their base-5 expansion).
> Until now I have a list of about 70 sequences of this form. I wouldn't be
> surprised if this goes beyond 150 sequences. I guess it would be nice to
> have some spot where they're all listed to then refer to that list in most
> of those sequences.
>
> I thought maybe to put them in xrefs of 1 but there are a lot of them.
> In addition, some sequences are a bit thin in info. Just name, sequence and
> thats merely it.
>
> What could be a good thing to do from here on out?
>
> Best,
> David
>
> --
> Seqfan Mailing list - http://list.seqfan.eu/
>

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