This is an excellent idea! For those not familiar with the area51 process, here's how you can help get this site off the ground:
Go to the site and click on "follow" in the upper left. The site needs at least 60 followers to proceed to the next phase of the creation process.
Upvote five of the questions, and perhaps ask a few questions of your own. The ...
Let me expand on this:
At the moment the site is very young. This means that we need to build up a core community in running the site. MSE is one of the main "big brothers" of HSM so asking for some help should not be a problem. If there are any questions related to the history of Math, although they are still on-topic here, it may be worth pointing out to ...
Mathematics puzzles are already on topic on Puzzling.SE and they form a large part of that site. I think that the golf part does not really work. The example questions you have so far are all on-topic on Puzzling.
For the purpose of this post I would consider these two two types of problems with typos and errors in the mathematical books:
You are not sure whether it is an error in the book or whether you misunderstood something. You need help with correcting a possible error, filling in missing steps, explaining some details, etc.
You are pretty sure that it is an ...
On HSM, we've been attracting some high-rep users (I won't say who) from relevant SE sites, such as Mathematics and Physics. One (from Physics) has taken an active role in shaping the site, in cases of moderation, namely, edits and close/reopen votes. It would be great if we could get some of the more experienced users on these science and math sites (don't ...
More of an update than an answer, but there is no question.
The Physics Problem Solving Area 51 proposal has since been closed by Stack Exchange staff. A comprehensive statement about this can be found in an answer by Robert Cartaino.
There had been a proposal for an SE site on Computer Algebra Systems (proposed Stack Exchange area) .
It was not successful.
You might consider the site on Computational Science. It has a numerical slant, but its scope even would include more algebraic aspects (at least last time I checked).
But as always, before you ask there, check the Help Center.
My puzzle questions in math.se are Evaluation of a slow continued fraction and Evaluation of a continued fraction ...
If problems such as these are welcome in math.se, that is great. But if not, perhaps we do need a "Mathematical Challenges" forum.
I followed the link the Meta.Physics.SE discussion given in the Question, and tried especially to understand the dictum "Presently Physics SE isn't meant for problem-solving."
One of the Related items shown there for it is this (fairly well-upvoted and answered) previous Meta.Physics post, Should we allow questions asking the mathematical solution to ...