collatz.rb

# http://en.wikipedia.org/wiki/Collatz_conjecture
def collatz(n)
  seq = Array.new
  while n > 1
    if n%2 > 0
      n = 3*n + 1
    else
      n = n / 2
    end #if
    seq.push n
  end #while
  return seq
end #def