collatz.rb

#!/usr/bin/env ruby -wKU

input = gets.chomp

if (input).to_i.integer?
  userInput = input
end

def collatzRecursive(number)
  number = number.to_i
  if (number == 1)
    puts "The Collatz Conjecture holds true!"
    exit
  elsif (number == 0)
    puts "The Collatz Conjecture is not true!"
    exit
  else
      # The number is even
      if ((number%2)==0) 
        number = number/2
        puts number
        collatzRecursive(number)
      # the number is odd
      elsif ((number%2)==1) 
        number = 3 * number + 1
        puts number
        collatzRecursive(number)
      end
    end
end

collatzRecursive(userInput)