@article{Lagarias2021,
  author    = {{Jeffrey C. Lagarias}},
  title     = {{The $3x+1$ Problem: An Overview}},
  year      = {{2021}},
  url       = {{https://arxiv.org/abs/2111.02635}},
  eprint    = {{2111.02635}},
  archiveprefix= {{arXiv}},
  primaryclass= {{math.NT}},
}