Lean mathematical components library
So I guess my thought is if you're going to practice writing proofs, start here: https://leanprover-community.github.io/
NOTE: The number of mentions on this list indicates mentions on common posts plus user suggested alternatives. Hence, a higher number means a more popular project.
There’s more to mathematics than rigour and proofs
1 project | news.ycombinator.com | 19 Apr 2022
The Lean Theorem Prover
1 project | news.ycombinator.com | 21 Mar 2022
Is there a formal proof that all integers can be expressed as the sum of four squares?
1 project | reddit.com/r/math | 19 Mar 2022
Why is simplicity so unreasonably effective at scientific explanation?
1 project | reddit.com/r/slatestarcodex | 13 Oct 2021
Tongue-in-cheek summaries of areas of mathematics
1 project | reddit.com/r/math | 15 Aug 2021