@article{Korec1992,
  author    = {{Ivan Korec}},
  title     = {{The $3x  +  1$ Problem, Generalized Pascal Triangles, and Cellular Automata}},
  journal   = {{Math. Slovaca}},
  year      = {{1992}},
  volume    = {{42}},
  pages     = {{547--563}},
  note      = {{MR 94g:11019}},
}