Talk:On-Line Encyclopedia of Integer Sequences

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For 2004 talk, see Talk:On-Line Encyclopedia of Integer Sequences/Archive2004.

OEIS linking syntax help[edit]

I would like to make a page along the lines of "Wikipedia:How to cite the OEIS" and include a link to that from this article. That page would explain the five different ways of citing and linking sequences in the OEIS and illustrate how to accomplish each one. PrimeFan 22:46, 14 July 2005 (UTC)

I've just spent 20 minutes searching for a template, convinced I'd seen one before. I'd welcome a synopsis. Hv 01:07, 17 August 2005 (UTC)
Using Sloane's A012345 as an example, the table below shows the five different ways. PrimeFan 19:32, 18 August 2005 (UTC)
[] [1]
[ A012345] A012345
[[OEIS:A012345]] OEIS:A012345
{{OEIS|id=A012345}} (sequence A012345 in the OEIS)
{{OEIS2C|id=A012345}} OEISA012345 This format is used for second and subsequent citations in a given article.
{{SloanesRef|sequencenumber=A012345}} "Sloane's A012345". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.  Seen in Arnold's_cat_map
I don't think the first two are really worth mentioning, and the third is a maybe - I'd class the templates as generally preferable, both for brevity and for the meta-information provided by having a reference to the template.
My own search turned up nothing via Wikipedia:Template, and I eventually stumbled across the templates in another page.
I certainly wouldn't have guessed what "OEIS2C" stood for, so some explanation somewhere would surely help. I did look in Wikipedia:Template messages/Links, so a reference there would be a start. Hv 02:03, 19 August 2005 (UTC)
I'm not even sure how things are sorted there at Template messages/Links. I'd have to carefully examine that page before I dared add anything to it. PrimeFan 20:39, 22 August 2005 (UTC)
How about mentioning these templates in the OEIS article? HenningThielemann (talk) 16:00, 9 January 2011 (UTC)
They are Wikipedia-specific, the article should be about OEIS itself and not list templates related to OEIS that can be used on Wikipedia. If someone created a page describing their use in the Wikipedia namespace, that would be okay. See also Wikipedia:SELFREF#Community_and_website_feature_references. Svick (talk) 19:14, 9 January 2011 (UTC)

Make encyclopedic[edit]

The current text has a mix of encyclopedic information and some very low-level "how-to" material. It needs to be cleaned up.... --Macrakis 23:31, 26 September 2005 (UTC)

Oh, how easy it is to complain about a problem and not do a thing to fix it! "It needs to be cleaned up," easy to say. "Make encyclopedic," easy it is to give that command.
At any rate, there isn't a problem. What you call "low-level how to" is a much better way to explain a potentially cryptic mathematical topic. A professional mathematician is given to saying things like "It is obvious that hence ." The lexicographic order of the OEIS is here explained far more clearly than in the OEIS itself! Robert Happelberg 22:06, 27 September 2005 (UTC)
OK, I've started fixing it. --Macrakis 01:51, 28 September 2005 (UTC)
Good job so far, Macrakis. Bob makes a good point, too. With Macrakis's and Bob's help, this article will eventually strike a good balance between spontaneity and professionalism. PrimeFan 15:48, 28 September 2005 (UTC)

Errors in the database[edit]

The article says "For a database of its magnitude, the OEIS is relatively free of errors. ... The more common mistakes in the OEIS occur in fields other than the sequence or signed field."

I have reason to doubt this. In early January 2000 or 2001, I took the database and ran a program on it to look for sequences whose terms were all prime except one. There were something like 100+ of these, perhaps as many as 300 (I can't remember for sure). I started checking these to see if the non-prime term was in error. I think I checked a little over 100 sequences. I found 10 or 11 errors. The errors were about what you would expect:

  1. transpose two digits
  2. spurious digit or digit omitted
  3. repeating the wrong digit, i.e. 355 instead of 335.
  4. leaving a comma in a term with four or more digits, making it appear to be two separate terms
  5. omitting a comma between two terms

So around 10% of the sequences I checked had obvious errors, and there could have been others. Bubba73 (talk), 23:26, 15 January 2006 (UTC)

Then I'm in trouble. For the vast majority of Wikipedia articles I've written about various kinds of numbers (e.g., Carol numbers, prime quadruplets), I've taken the listing from the OEIS. In a few cases I take the listing from Mathematica.
For my part, I will double-check the sequences listed in articles I've written. For your part, could you re-run your "sequences whose terms were all prime except one" search on a more recent copy of the table? PrimeFan 21:05, 17 January 2006 (UTC)
Bubba73 did an interesting approach for finding errors in the database! Another way might be to check the sequence samples against the given PARI, Mathematica, and Maple code pieces. HenningThielemann (talk) 16:26, 9 January 2011 (UTC)

Self-referential paradox[edit]

In the 'Self-referentiality' section, "sequences A053873, n is in An, and A053169, n is not in An" are referred to as "delightfully paradoxical" because "[t]he paradox is, which sequences do 53169 and 53873 belong to?" Surely only 53169 in A053169 gives rise to a paradox?

Sendhil 01:24, 20 July 2006 (UTC)

Alright, prove that 53873 does belong in OEISA053873. Anton Mravcek 16:41, 20 July 2006 (UTC)
Or prove that it does not.
And 53169 not in OEISA053169 also gives rise to a paradox --Rumping 19:12, 22 September 2007 (UTC)
Looking at this a year later, I stand by calling these issues "paradoxical." My problem now would be the word "delightfully." I find these paradoxes delightful but that might just be my POV. Some people might find these annoying. Anton Mravcek 20:32, 22 September 2007 (UTC)
I don't see anything paradoxical regarding 53873. It's true that we can't prove whether 53873 is in the sequence or not, but that just means that the sequence is not completely defined. On the other hand, I believe that A053169 is truly a paradox: both the assumptions that 53169 belongs to the sequence and that it doesn't lead to contradictions. -- Jitse Niesen (talk) 14:15, 29 December 2008 (UTC)
I have re-written the section to try to improve its clarity. I removed the "delightfully paradoxical" phrase because it seemed to me to be an unencyclopedic description. I agree with Jitse Niesen - A053873 cannot be completed unless we create an axiom that says "53873 is (or is not) a member of A053873", but only A053169 is truly paradoxical. Gandalf61 (talk) 16:22, 26 January 2009 (UTC)

In the unreferenced quote attributed to Sloane in the self-referentiality section of the article, the article source contains an HTML nonbreaking space before the exclamation mark in "known to 11 terms !" Is this a punctuation given in the quotation source? if not, I can't see that it should be there: it's not going to be misconstrued as a factorial, for instance. --Kay Dekker (talk) 22:12, 27 February 2010 (UTC)


The article currently uses ''n'' (n) for indices and A_''n'' (A_n) for members. I think this looks bad, and doesn't match the OEIS (which uses no italics). The 'right' way would seem to be n and A_n, or perhaps <code>n</code> (n) and <code>A_n</code> (A_n).

There is value to italicizing n to draw it out in the text, but when paired with the upright A it has a very unpolished appearance.

CRGreathouse (t | c) 15:58, 27 January 2009 (UTC)

what does at&t have to do with this?[edit]

if someone knows the history of how at&t is related to this topic, it would be useful to add. i clicked a link on a link on a wiki page and was taken to an att website, which prompted me to look for more info on this page. the company obviously have something to do with the sequence ecyclopedia, but there is no real reference to this fact in this article. HantaVirus (talk) 17:27, 27 July 2009 (UTC)

The database is hosted on an AT&T web site and run by Neil Sloane, a long-time AT&T employee. I've added some text to the article explaining that. —David Eppstein (talk) 17:32, 27 July 2009 (UTC)

Does anyone want to use footnotes instead of inline links to link OEIS sequences?[edit]

A suggestion to change the template in that way has been made at Template talk:OEIS#This is an external link. Lipedia (talk) 15:57, 19 October 2011 (UTC)

Normalizing the sequences for lexicographic order[edit]

How is the normalization done? I did a cursory search but could not find out how. Thank you in advance. — Preceding unsigned comment added by Anorderofmagnitude (talkcontribs) 00:17, 16 May 2013 (UTC)

Did you read the article's section on Lexicographical ordering?!?
The examples given start like this:
  • Sequence #1: 2, 3, 5, 7, 11, 13, ...
  • Sequence #2: 2, 3, 5, 7, 11, 101, ...
  • Sequence #3: [0, 1, 1], 2, 3, 5, 8, ...
  • Sequence #4: [1], 2, 4, 7, ...
  • Sequence #5: [1], [−]3, [−]8, ...
The initial 0's, 1's, and the numbers' signs (which i've explicitly marked above) are ignored, thus the order is #1, #2, #3, #4, #5 instead of #3, #5, #4, #1, #2.
-- Jokes Free4Me (talk) 10:25, 16 May 2013 (UTC)
Thank you much. Yes I did read the section. First the square brackets above made the sequencing order very clear. Second maybe the we can change "ignoring initial zeros or ones" to "ignoring initial zeros and ones". I was only ignoring the initial "0" in sequence #3. — Preceding unsigned comment added by Anorderofmagnitude (talkcontribs) 00:35, 17 May 2013 (UTC)
Okay, i've changed the article to make it all clear. Is it okay now? :) -- Jokes Free4Me (talk) 17:15, 17 May 2013 (UTC)
Yes thank you. — Preceding unsigned comment added by Anorderofmagnitude (talkcontribs) 19:27, 17 May 2013 (UTC)

how useful is it in actual research?[edit]

Are there any examples of research in mathematics published in fairly prestigious journals which was aided by OEIS? — Preceding unsigned comment added by (talk) 12:27, 3 September 2014 (UTC)

Look at PrimeHunter (talk) 13:20, 3 September 2014 (UTC)