Collatz conjecture

Rosetta Code is removing this draft task in favour of Hailstone sequence. DO NOT add to this page as it is going away.

Collatz conjecture is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

These programs calculate the Collatz sequence for a given integer, and stop if 1 is reached.

These programs were written before this task was created; as such, the specific actual requirements of this task have not yet been determined.

Befunge

<lang befunge>&>:.:1-|

 >3*^ @
 |%2: <
v>2/>+</lang>

Excel

   In cell A1, place the starting number.
   In cell A2 enter this formula =IF(A1/2=ROUND(A1/2,0),A1/2,A1*3+1)
   Drag and copy the formula down until 4, 2, 1

Ioke

<lang ioke>collatz = method(n,

 n println
 unless(n <= 1,
   if(n even?, collatz(n / 2), collatz(n * 3 + 1)))

)</lang>