Updates Getting banned from Project Euler by 
Ciro Santilli 37 Created 2025-10-27 Updated 2025-11-05
Ciro Santilli 37 Created 2025-10-27 Updated 2025-11-05I have been banned from Project Euler for life, and cannot login to my previous account projecteuler.net/profile/cirosantilli.pn
The ban happened within 12 hours of me publishing a solution to Project Euler problem 961 github.com/lucky-bai/projecteuler-solutions/pull/94 which was one-shot by a free GPT-5 account as MathArena had alerted me to being possible: matharena.ai/?comp=euler--euler&task=4&model=GPT-5+%28high%29&run=1
The problem leaderboard contains several people solved the problem within minutes of it being released, so almost certainly with an LLM.
The "secret club" mentality is their only blemish, and incompatible with open science.
They should also make sure that LLMs don't one shot their future problems BEFORE publishing them!
A naive
T in Python is:from collections import deque
def T(a: int, b: int, N: int) -> int:
total = a
q = deque([a] * (a - 1))
is_a = False
for i in range(N - 1):
cur = q.popleft()
total += cur
q.extend([a if is_a else b] * cur)
is_a = not is_a
return total
assert T(2, 3, 10) == 25
assert T(4, 2, 10**4) == 30004
assert T(5, 8, 10**6) == 649987122332223332233 which has 14 digits.Maybe if
T is optimized enough, then we can just bruteforce over the ~40k possible sum ranges 2 to 223. 1 second would mean 14 hours to do them all, so bruteforce but doable. Otherwise another optimization step may be needed at that level as well: one wonders if multiple sums can be factored out, or if the modularity can of the answer can help in a meaningful way. The first solver was ecnerwala using C/C++ in 1 hour, so there must be another insight missing, unless they have access to a supercomputer.The first idea that comes to mind to try and optimize
T is that this is a dynamic programming, but then the question is what is the recurrence relation.The sequence appears to be a generalization of the Kolakoski sequence but to numbers other than 1 and 2.
maths-people.anu.edu.au/~brent/pd/Kolakoski-ACCMCC.pdf "A fast algorithm for the Kolakoski sequence" might provide the solution, the paper says:and provides exactly a recurrence relation and a dynamic programming approach.
www.reddit.com/r/dailyprogrammer/comments/8df7sm/20180419_challenge_357_intermediate_kolakoski/ might offer some reference implementations. It references a longer slide by Brent: maths-people.anu.edu.au/~brent/pd/Kolakoski-UNSW.pdf
www.reddit.com/r/algorithms/comments/8cv3se/kolakoski_sequence/ asks for an implementation but no one gave anything. Dupe question: math.stackexchange.com/questions/2740997/kolakoski-sequence contains an answer with Python and Rust code but just for the original 1,2 case.
People who do cool open tech stuff when don't need money anymore are awesome:
- François Chollet, project founder: www.linkedin.com/in/fchollet/ 9 years at Google from 2015 to 2024. He founded ARC while he was still at Google though, so maybe doesn't coun
- Cristiano Calgano from cristianoc/arc-agi-2-abstraction-dataset. Imperial College London researcher who founded a formal verification company and sold it to Facebook where he staid for 7 years
- Benjamin Crouzier from Tufa Labs
Benjamin has a masters in Computer Science and applied ML to quant finance previously, tufalabs.ai/team.html mentions:
From another awesome retired tech bro that does this project for fun.
Cool website tracking the status of varios
Welcome to my home page!
Welcome to my home page!
Pinned article: Introduction to the OurBigBook Project
Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
Intro to OurBigBook
. Source. We have two killer features:
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- a Wikipedia where each user can have their own version of each article
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This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
Figure 1. Screenshot of the "Derivative" topic page. View it live at: ourbigbook.com/go/topic/derivativeVideo 2. OurBigBook Web topics demo. Source. - local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
- to OurBigBook.com to get awesome multi-user features like topics and likes
- as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
Figure 3. Visual Studio Code extension installation.
Figure 4. Visual Studio Code extension tree navigation.
Figure 5. Web editor. You can also edit articles on the Web editor without installing anything locally.Video 3. Edit locally and publish demo. Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.Video 4. OurBigBook Visual Studio Code extension editing and navigation demo. Source. 
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All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact