Does the Modified Collatz Conjecture Always End in 1, 5, or 17?

  • #1
Dries vanlandschoot
2
1
Homework Statement
3x+1 =odd. If even x÷2
Relevant Equations
What if we use 3x-1 and x÷2
Did some calculations and with 3×-1 i Always get 5.is this correct?
 
Physics news on Phys.org
  • #2
Umm... What? Please elaborate. Maybe some examples? I don't know what your question is.

But: 3x + 1 = (odd) => 3x + 1 - 2 = (odd) -2, and (odd) -2 = (odd) => 3x - 1 = (odd).
 
  • #3
Collatz conjecture. Look up in Wikipedia.unsolved problem in math
 
  • Like
Likes DaveE
  • #4
6, 3, 8, 4, 2, 1, 2, 1....?
 
  • Like
Likes FactChecker
  • #5
Dries vanlandschoot said:
Did some calculations and with 3×-1 i Always get 5.is this correct?
No. Starting at 6 you get the sequence above in DaveE's post.
Starting at 7 we get: 7, 20, 10, 5, 14, 7...
 
  • Like
Likes WWGD
  • #6
Drakkith said:
No. Starting at 6 you get the sequence above in DaveE's post.
Starting at 7 we get: 7, 20, 10, 5, 14, 7...
And there's the proof we won't hit 2. Once we hit the 2nd 7, we'll be looping indefinitely.
 
  • #7
Finding a looping example to the original collatz rules will disprove it as a theorem.
 
  • Like
Likes WWGD
  • #8
Recent Sciam article on Collatz

https://www.scientificamerican.com/article/the-simplest-math-problem-could-be-unsolvable/

At first glance, the problem seems ridiculously simple. And yet experts have been searching for a solution in vain for decades. According to mathematician Jeffrey Lagarias, number theorist Shizuo Kakutani told him that during the cold war, “for about a month everybody at Yale [University] worked on it, with no result. A similar phenomenon happened when I mentioned it at the University of Chicago. A joke was made that this problem was part of a conspiracy to slow down mathematical research in the U.S.”

The Collatz conjecture—the vexing puzzle Kakutani described—is one of those supposedly simple problems that people tend to get lost in. For this reason, experienced professors often warn their ambitious students not to get bogged down in it and lose sight of their actual research.
 
  • #9
17 is interesting (slightly); it increases and then loops back to itself. And, yes, some end at 5.

1710310378062.png
 
  • #10
... and still unsolved!
 
  • #11
DaveE said:
17 is interesting (slightly); it increases and then loops back to itself. And, yes, some end at 5.

View attachment 341703
Maybe we can tweak it into a new result that this version will end in 1,5 or 17? Just a Wil guess. Someone used to call it the " Law of Small Numbers"; wild guesses from limited data.
 

FAQ: Does the Modified Collatz Conjecture Always End in 1, 5, or 17?

What is the Modified Collatz Conjecture?

The Modified Collatz Conjecture is a variation of the original Collatz Conjecture. In this version, the sequence is generated by the following rules: if the number is even, divide it by 2; if the number is odd, multiply it by 3 and add 1, then divide by 2. The conjecture posits that no matter what positive integer you start with, the sequence will eventually reach 1, 5, or 17.

How is the Modified Collatz Conjecture different from the original Collatz Conjecture?

The original Collatz Conjecture involves iterating the sequence by dividing even numbers by 2 and replacing odd numbers with 3n + 1. The Modified Collatz Conjecture adds an additional step for odd numbers: after multiplying by 3 and adding 1, you then divide by 2. This modification changes the dynamics of the sequence and, according to the conjecture, leads to the sequence eventually reaching 1, 5, or 17.

Has the Modified Collatz Conjecture been proven?

As of now, the Modified Collatz Conjecture, like the original Collatz Conjecture, has not been proven. It remains an open problem in mathematics. While it has been tested for many numbers and no counterexamples have been found, a formal proof that it holds for all positive integers is still lacking.

Why are the numbers 1, 5, and 17 special in the Modified Collatz Conjecture?

In the Modified Collatz Conjecture, the numbers 1, 5, and 17 are special because they are the conjectured endpoints of the sequence. When the sequence reaches one of these numbers, it enters a loop or a state where it will repeatedly cycle through the same values. For example, starting from 1, the sequence will stay at 1; starting from 5, it will cycle through 5, 8, 4, 2, 1; and starting from 17, it will eventually cycle through a series of numbers that return to 17.

What is the significance of studying the Modified Collatz Conjecture?

Studying the Modified Collatz Conjecture, like the original Collatz Conjecture, is significant because it touches on deep questions about number theory, iterative processes, and mathematical patterns. Understanding why certain sequences behave in specific ways can provide insights into more complex mathematical phenomena. Additionally, exploring these conjectures can lead to the development of new mathematical techniques and tools.

Back
Top