Talk:Self number

A fact from Self number appeared on Wikipedia's Main Page in the Did you know column on 6 August 2004. The text of the entry was as follows:

Did you know... that a self number is an integer that cannot be generated by any other integer added up to its digits?

A record of the entry may be seen at Wikipedia:Recent additions/2004/August.

Wikipedia

Mathematics

	Mathematics portal This article is within the scope of WikiProject Mathematics, a collaborative effort to improve the coverage of mathematics on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.MathematicsWikipedia:WikiProject MathematicsTemplate:WikiProject Mathematicsmathematics articles
???	This article has not yet received a rating on the project's priority scale.

Numbers

	This article is within the scope of WikiProject Numbers, a collaborative effort to improve the coverage of Numbers on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.NumbersWikipedia:WikiProject NumbersTemplate:WikiProject NumbersNumbers articles
???	This article has not yet received a rating on the project's importance scale.

Any applications? - Highwind

Probably not. But mathematicians and number aficionados are very interested in them just the same. PrimeFan 22:50, 6 Aug 2004 (UTC)

[Comment deleted. I was looking at the (ambiguous) words and not the numbers. Pronoun reference problem fixed.] Major Danby, 18 Aug 2005

Colombian and Columbian numbers

I'm embarrassed about this, but I have to admit it. For the first draft of this article, I wrote "self number or Colombian number," where I should have written "self number or Columbian number." That's the spelling given both by Mathworld and the OEIS. It's an alternate term, but there is still a lot of older literature that uses it, so I apologize for screwing it up. PrimeFan 18:27, 13 December 2005 (UTC)[reply]

k

What does the k stand for in the formula? --Shandris 07:11, 16 May 2006 (UTC)[reply]

I think it's just a convenient running variable. m might be just as suitable. The reason n is not used is that it would lead one to expect that the recurrence relation gives all self numbers, when in fact it just gives an incomplete though infinite list. PrimeFan 15:57, 17 May 2006 (UTC)[reply]

"Other number"

Is there a technical term? ie, "The -blah- of 30 in base ten is 24 because 24+2+4=30.". Also, why aren't all single-digit numbers self-numbers? ✍ (talk) 17:40, 1 June 2009 (UTC)[reply]

I don't know a term for the other number(s). There may be more than one, for example for 101 = 91+9+1 = 100+1+0+0. Even single-digit numbers d > 0 cannot be self numbers, because d/2 can be used as the other number: d/2+d/2 = d. PrimeHunter (talk) 18:08, 1 June 2009 (UTC)[reply]

According to Trotter - Charlene numbers, Kaprekar who first described the self number called such an other number a generator, so "A generator of 30 in base ten is 24 because 24+2+4=30." Trewal (talk) 10:28, 2 June 2009 (UTC)[reply]

Kaprekar's expression is wrong?

I found if I use Kaprekar's expression to compute self number, 29 is also self number. But 19 is a generator of 29. So anybody know what's wrong with this problem? —Preceding unsigned comment added by 218.22.21.11 (talk) 11:28, 18 October 2010 (UTC)[reply]

I assume you refer to Self number#Effective test. When I use it I get the self numbers given in the lead: 1, 3, 5, 7, 9, 20, 31, 42, 53, 64, 75, 86, 97, 108, 110, 121, 132, 143, 154, 165, 176, 187, 198, 209, 211, 222, 233, 244, 255, 266, 277, 288, 299, 310, 312, 323, 334, 345, 356, 367, 378, 389, 400, 411, 413, 424, 435, 446, 457, 468, 479, 490, 501, 512, 514, 525. There is no 29 so I guess you evaluated the expression incorrectly. PrimeHunter (talk) 12:21, 18 October 2010 (UTC)[reply]