The Simplest Math Problem No One Can Solve - Collatz Conjecture

Veritasium · 46.7M views · 2021 · 22:09

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Why Mathematics Stack Exchange recommends it

Mathematics Stack Exchange users cite it as the source of their questions about Collatz sequences, loops, and visual patterns, and use its timestamps to point at specific claims.

Recommended by 0 people across 0 different months, 2021 to 2025.

What it is

A Veritasium explainer on the Collatz conjecture (the 3x+1 problem), showing how simple the rule is and why it has resisted proof. It covers partial results from Terence Tao, an interview with Prof. Alex Kontorovich, and a look at Conway's Fractran and related undecidability ideas.

Cited in 1 Wikipedia article, including Collatz conjecture.

What people said

Cites Mr Tsjolder from codidact · 2021-08 · Mathematics Stack Exchange · on “Why does this “proof” for the Collatz conjecture not work?”

After seeing a video [this video] on the Collatz conjecture [LINK] , I kind of played around with it a bit and found the following result (which can be shown by induction): $$\underbrace{f \circ \ldots \circ f}_{N \text{ times}}(2^N x - 1) = 6^{\left\lceil\frac{N}{2}\right\rceil} x - 2 + (N + 1) \mathbin{\mathrm{mod}} 2.$$ If the Collatz conjecture were true, then $\forall x \in \mathbb{N} : \lim_\limits{N \to \infty} \underbrace{f \circ \ldots \circ f}_{N \text{ times}}(x) = 1$ . However, the result above would imply that for any number of function applications, $N$ , there is an (infinite set of) input(s) that will be larger than the inputs and therefore can not be one. So, even if $N \to \inft

Cites Fuzzy_Bunnys · 2021-10 · Mathematics Stack Exchange · on “Veritasium on Collatz — Clarification about loops”

I have watched Veritasium [LINK] 's recent video [this video] on the Collatz conjecture. At 11m17s [this video] , he mentions that if you can show that for every seed value, there is at some point a number less than the seed value in the sequence generated by the Collatz function, then you've proven the conjecture. Doesn't this condition preclude a loop? If I have some loop, won't it at some point include a reduction in value? For example, if I have a loop that goes $12 \to 15 \to 64 \to 72 \to 12$ can't I just say, well $72$ is my seed value, since $12 < 72$ , then $72$ must reduce, and all the other values in the loop reduce as well? I understand its a popular video, and it's not a precise definitio

Cites Iffat Iqbal · 2025-02 · Mathematics Stack Exchange · on “Pattern in perfect squares? Has this been found before?”

I have a snow day here in Toronto and I wanted to kill some time by rewatching the very well-known Veritasium video on the Collatz conjecture [this video] . I found this strange pattern at around 15:45 where the perfect squares kind of form a ripple pattern while you increase the bounds and highlight where the perfect squares are. Upon further inspection, I also saw that these weren't just random pixels either, they were the actual squares. Why might this happen? Here is what it looks like, these sideways parabola-like structures expand and are followed by others similar structures from the right. [LINK] [LINK] My knowledge of math is capped off at the Linear Algebra I am learning right now in Gr