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Collatz Conjecture (OEIS A006577)

This is the Collatz Conjecture (OEIS A006577):

Start with an integer n> 1.
Repeat the following steps:
- If n is even, divide it by 2.
- If n is odd, multiply it by 3 and add 1.

It is proven that for all positive integers up to 5 * 2⁶⁰, or about 5764000000000000000, n will eventually become 1.

Your task is to find out how many iterations it takes (of halving or tripling-plus-one) to reach 1.

Relevant xkcd :)

Rules:

Shortest code wins.
If a number < 2 is input, or a non-integer, or a non-number, output does not matter.

Test cases

2 -> 1
16 -> 4
5 -> 5
7 -> 16

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…Try to optimize your score. For instance, answers to code-golf challenges should attempt to be as short as possible. You can always include a readable version of the code in addition to the competitive one. Explanations of your answer make it more interesting to read and are very much encouraged.
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\$\begingroup\$ -5 bytes with -rR and new register commands \$\endgroup\$

lyxal
– lyxal ♦

2019年12月13日 20:24:15 +00:00
Commented Dec 13, 2019 at 20:24

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