Talk:Full reptend prime

Etymology of reptend
Does anybody know the etymology of the term reptend? I could not find it in any dictionary. HannsEwald (talk) 11:03, 5 December 2007 (UTC)

I now believe that the term is in error and should be repetend instead, which comes from Latin repetere and means repeating. Google gives about three times as many hits for repetend as for reptend. I propose to rename this article. HannsEwald (talk) 11:59, 19 December 2007 (UTC)


 * Google has 338 hits on "full reptend prime" and only 2 on "full repetend prime", so the former is clearly the accepted name for this type of prime. By the way, 1 of the 2 with "repetend" doesn't use that term but is only in the Google hits because the other one links to it with that term. Wikipedia should use the accepted name no matter whether another name might appear to make more sense. See Naming conventions (common names). PrimeHunter (talk) 12:55, 19 December 2007 (UTC)


 * I also believe that reptend is an error and should be repetend. While occurrences of full reptend prime do currently outnumber full repetend prime in Google, ocurrences of repetend by itself currently outnumber reptend by a margin of 4 to 1.  I have consulted several hardcopy general dictionaries and math dictionaries.  None of them had reptend but all of the general dictionaries and some of the math dictionaries had repetend.  The general dictionaries all have reptant and/or reptation, both of which mean "crawling" and are from the Latin reptare "to creep".  So it appears to me that reptend should mean something like "that which is to be crawled upon" rather than "that which is to be repeated".  The only hardcopy source I can find that contains reptend is Eric Weisstein's CRC Encyclopedia of Math.  Therefore I believe that reptend was introduced in error by this author with the first edition of this work in 2000.  Further I believe that full reptend prime currently outpolling full repetend prime is a result of this error being propagated in MathWorld, which was based on Weisstein's encyclopedia and is now the most highly regarded source of math information on the web.  — Preceding unsigned comment added by Kevin Carmody (talk • contribs) 21:14, 13 December 2013 (UTC)


 * It doesn't matter to Wikipedia what the origin of a name is. It matters what people actually call it, and that is clearly full reptend prime. A Google scholar search gives several results for "full reptend prime" and none for "full repetend prime". PrimeHunter (talk) 00:34, 14 December 2013 (UTC)


 * If we accept the validity of the word reptend, then the problem is that neither Google nor WP fully recognize reptend and repetend as synonyms. A WP search for reptend by itself gives a list of articles containing that form of the word only and does not mention the Repeating decimal article, while a search for repetend redirects to the Repeating decimal article.  A search for full repetend prime turns up no results but asks if you meant full reptend prime.  I suggest adding redirects to handle both forms of the word, and indicating in the articles that both forms are synonyms. Kevin Carmody (talk) 04:04, 14 December 2013 (UTC)


 * I'm not saying we accept the validity of the word reptend by itself. I'm saying we accept the validity of the 3-word term full reptend prime, since nearly all sources use that term. The article only uses reptend as part of this term. Redirects don't have strict rules and we could make them here, but reliable sources are required to claim in articles that reptend and repetend are synonyms. PrimeHunter (talk) 13:41, 15 December 2013 (UTC)


 * I realize you were not talking about reptend by itself, but I am, because the word reptend in the term full reptend prime is clearly an instance of the general term reptend / repetend. Therefore, for consistency, the two should be tightly linked, but right now they are not.  I don't understand what you mean by "reliable sources" being "required to claim" that the two words are synonyms.  I think that "sources" normally means authors of works that WP references, and these authors have no such requirement.  Do you mean WP editors?  The current articles don't say this and I think they should.  Don't you agree? Kevin Carmody (talk) 11:39, 16 December 2013 (UTC)


 * I meant that Wikipedia requires reliable sources in order to claim in articles that reptend and repetend are synonyms. Currently we do what the sources do: Define "full reptend prime" and not mention there is something called "repetend" alone, with a different spelling. Wikipedia is source-based and has policies against WP:SYNTHESIS. We could mention what repetend means and let the readers conclude on their own that it's where "reptend" must come from. And Repeating decimal could link to Full reptend prime. PrimeHunter (talk) 02:33, 18 December 2013 (UTC)


 * If you think that a claim that repetend and reptend are synonyms violates WP:SYNTHESIS (aka WP:SYNTH), then I suggest you take a look at WP:What SYNTH is not. Check out the following sections: SYNTH is not a policy, SYNTH is not just any synthesis,  SYNTH is not unpublishably unoriginal, and especially SYNTH is not a rigid rule.


 * From the unpublishly unoriginal section: "Suppose you took this claim to a journal that does publish original research. Would they (A) vet your article for correctness, documentation, and style, and publish it if it met their standards in those areas? Or would they (B) laugh in your face because your 'original research' is utterly devoid of both originality and research, having been common knowledge in the field since ten years before you were born? If you chose (B), it's not original research -- even if it violates the letter of WP:SYNTH."


 * From the rigid rule section: "Wikipedia doesn't have [rigid rules], supposedly. But if a policy gets enforced zealously, it can be hard to tell the difference. The solution is not to enforce policies zealously. Never use a policy in such a way that the net effect will be to stop people from improving an article."


 * While there are certainly cases where WP needs to guard against synthesis, I don't think this is one of them. The statement that repetend and reptend are synonyms is common knowledge in the field and as such does not need to be referenced.  Adding this statement would substantially improve the article.Kevin Carmody (talk) 10:38, 18 December 2013 (UTC)

long primes & palindromicity
has anyone studied whether all strictly non-palindromic numbers which are prime are also long primes and if their's any connection between these two properties? Numerao (talk) 22:39, 8 March 2008 (UTC)

No, 53 and 79 aren't, their period lengths are both only 13. — Preceding unsigned comment added by 61.219.149.55 (talk) 06:08, 6 May 2014 (UTC)

Relation to safe primes
Safe primes should theoretically be more likely to be full reptend primes. Afaik the reptend length of a prime number is always a divisor of p-1, and if p is a safe prime this can only be 1, 2, (p-1)/2 or p-1. For an "unsafe" prime, the reptend length has more options (e.g. 1/13 may have a 1, 2, 3, 4, 6 or 12 digit reptend). The lists of full reptend primes in various bases seem to support this at least for the smaller numbers.

However, in Cunningham chains, this does not appear to translate into a higher likelihood of being full reptend for the later members. E.g. in decimal 179 is full reptend but 359, 719, 1439 and 2879 all aren't, despite being safe primes "higher" in the Cunningham chain (89, 179, 359, 719, 1439, 2879). --2003:E7:7730:FF75:4D9F:9EAC:2BD2:8C5C (talk) 22:03, 29 August 2020 (UTC)

Period of 1/43 in binary
The prime 43 is congruent to 3 (mod 8), so 2 is not a quadratic residue modulo 43. So why isn't 43 a full reptend prime in binary when it is supposed to be? Fomfeider (talk) 16:55, 20 September 2021 (UTC)
 * No, it's not "supposed to be". The statement is "all of them [full reptend primes] are of form 8k + 3 or 8k + 5", not "all primes of the form 8k + 3 or 8k + 5 are full reptend primes". Phil Bridger (talk) 16:42, 22 September 2021 (UTC)