mathlib

4f484a1e - feat(archive/100-theorems-list): Sum of the Reciprocals of the Triangular Numbers (#2692)

feat(archive/100-theorems-list): Sum of the Reciprocals of the Triangular Numbers (#2692) Adds a folder `archive/100-theorems-list`, moves our proof of 82 into it, and provides a proof of 42. There's a readme, I haven't really thought about what should go in there. Co-authored-by: Yury G. Kudryashov <urkud@urkud.name>