do -- find some attractive numbers - numbers whose prime factor count is prime

   -- Returns true if x is prime, and false otherwise
   function isPrime (x)
      if x < 2 then return false end
      if x < 4 then return true end
      if x % 2 == 0 then return false end
      for d = 3, math.sqrt(x), 2 do
         if x % d == 0 then return false end
      end
      return true
   end

   -- Compute the prime factors of n
   function factors (n)
      local facList, divisor = {}, 1
      if n > 1 then
         while not isPrime(n) do
            while not isPrime(divisor) do ++ divisor end
            while n % divisor == 0 do
               n //= divisor
               facList:insert(divisor)
            end
            ++ divisor
            if n == 1 then return facList end
         end
         facList:insert(n)
      end
      return facList
   end

   -- Main procedure
   local count = 0
   for i = 1, 120 do
      if isPrime(#factors(i)) then
         ++ count
         io.write( string.format( "%6d", i ), if count % 12 == 0 then "\n" else "" end )
      end
   end
end