Wikipedia:Reference desk/Archives/Mathematics/2016 March 3

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March 3

Sum of unitary divisors

Given the factorization of a positive integer, is there an equation for the sum of its Unitary divisors the way there is for the sigma function (divisor function)? Bubba73 ^{You talkin' to me?} 02:26, 3 March 2016 (UTC)

MathWorld's Unitary Divisor Function article gives $\sigma _{k}^{*}(p_{1}^{\alpha _{1}}p_{2}^{\alpha _{2}}\ldots )=(1+p_{1}^{k\alpha _{1}})(1+p_{2}^{k\alpha _{2}})\ldots$. Set k=1 if you're interested in the sum of the 1st powers. Egnau (talk) 21:01, 3 March 2016 (UTC)

Thanks, that is what I need! Bubba73 ^{You talkin' to me?} 21:07, 3 March 2016 (UTC)

Resolved

Polymath project

I don't know where to go, so I'm posting this here. There has been another polymath project solved! Can someone add this information to the "Problem solved" section of the article please? I think it can go under the heading of "Polymath proposal problem" under "Problem solved" section. This problem was going to become a polymath project, but someone else proved it so quickly before it becoming a polymath project (with number). However, I think it is another achievement worth mentioning in the article. Due to my limited mathematics background, I don't think I'm able to write about it as well as someone else with a major in mathematics or advanced knowledge in mathematics. If not, does someone know anyone, who has a strong background in mathematics, that currently still active on Wikipedia? So that I can ask him/her out personally. Thank you! Pendragon5 (talk) 23:11, 3 March 2016 (UTC)

This is a reasonable place for this request, but probably better are Wikipedia talk:WikiProject Mathematics and Talk:Polymath Project. People interested in the article will be watching the latter. (I don't have anything to say about the actual subject matter). -- Meni Rosenfeld (talk) 00:26, 4 March 2016 (UTC)

I'm not sure anyone pays attention to Talk:Polymath Project. Wikipedia talk:WikiProject Mathematics seems like a good option. I'll try that out later. Thank you! Pendragon5 (talk) 07:05, 4 March 2016 (UTC)

It's been a while since I was involved in anything on Wikipedia outside WP:RD/Ma, but as I recall, by default any page one edits is automatically added to their watchlist (together with the talk page). So all the people here should see edits to the talk page in their watchlists, and they are the people most likely to care and have relevant knowledge about the topic. -- Meni Rosenfeld (talk) 10:19, 4 March 2016 (UTC)

That is not the default behavior, but it can by enabled by checking "Add pages and files I edit to my watchlist" on the "Watchlist" tab of your user preferences. That will cause the "Watch this page" checkbox under the edit summary box to be pre-checked for all edits. More details at Help:Watchlist. -- ToE 14:21, 4 March 2016 (UTC)

I haven't fully read the linked article, as I got stuck at P = {t, t+1, t^2+t+1, ...}
That list starts with t, then adds 1 then adds t^2. It isn't obvious to me what the sequence represented by ... is. Does this article make any sense? -- SGBailey (talk) 15:19, 4 March 2016 (UTC)

They are the irreducible polynomials over the field with two elements. --JBL (talk) 15:25, 4 March 2016 (UTC)