@article{Bernstein1994,
  author    = {{Daniel J. Bernstein}},
  title     = {{A Non-Iterative 2-adic Statement of the $3x +  1$ Conjecture}},
  journal   = {{Proc. Amer. Math. Soc.}},
  year      = {{1994}},
  volume    = {{121}},
  pages     = {{405--408}},
  note      = {{MR 94h:11108}},
}