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A sea of non-experts is only helpful for learning if you are further behind on the trail and have obvious questions.

That said, a community is good for other things. And many times the issues people have are "obvious" questions.

There is a Discord server for the OSSU computer science cirriculum that is pretty active. https://github.com/ossu/computer-science

It's not strictly mathematics, but obviously there are a number of mathematics courses in the cirriculum.