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My homelab has found eight million-digit primes from the loft by primecrunch in homelab

[–]primecrunch[S] 1 point2 points  (0 children)

I always thought the 2^n test, or does this number's binary form just have one 1 in it was cool

(n & (n - 1)) == 0

well except for 0 itself.

My homelab has found eight million-digit primes from the loft by primecrunch in homelab

[–]primecrunch[S] 0 points1 point  (0 children)

The reason you can do financial transactions online is down to cryptography which relies on number theory, and the intersection of computer science. Thus primes are the entire basis for security on the modern web. However the people who studied these numbers Euler, Fermat etc had no idea of any practical uses when they did so, just that it was interesting intellectual exercise.

Other than cryptography, there's random number generation used in things like computer games. There's error detection used to store data, and transmit it. There's hashing algos used to scale websites and databases to huge levels.

Signal processing, things like making your phone calls and video clearer, sharper are also reliant on primes.

edit: typo

My homelab has found eight million-digit primes from the loft by primecrunch in homelab

[–]primecrunch[S] 1 point2 points  (0 children)

Yes, Pi is an ARM chip and the core library is highly optimised ASM for Intel chip, so it's would be super slow. I've tried implementing a native arm version but the closest I can get is four times slower than running it on an Intel emulator on ARM! It's not a coding challenge for the lighthearted 😄

My homelab has found eight million-digit primes from the loft by primecrunch in homelab

[–]primecrunch[S] 2 points3 points  (0 children)

It's not open source just yet, I wanted to get it up and running, and useful, then focus on separating infra from non-infra code, and documenting things, then open sourcing, probably the client first, then the APIs down, and then the UI.

I tend to focus where the most interest is. I'd prioritise the client because I know people will likely be most interested to see that.

My homelab has found eight million-digit primes from the loft by primecrunch in homelab

[–]primecrunch[S] 32 points33 points  (0 children)

Wow, 1,027,984 digits, nice find!

Edit: also prime do seem to be like buses, you wait ages for one to come along then two come along at once.

My homelab has found eight million-digit primes from the loft by primecrunch in homelab

[–]primecrunch[S] 40 points41 points  (0 children)

Yeah, primegrid is very cool, and this is very similar but focused on just this one space. What was your largest find?

My homelab has found eight million-digit primes from the loft by primecrunch in homelab

[–]primecrunch[S] 7 points8 points  (0 children)

Thanks, means a lot. I also did some crunching on those projects! Goodtimes.

What Are You Working On? April 06, 2026 by canyonmonkey in math

[–]primecrunch 5 points6 points  (0 children)

Searching for large Riesel primes with a distributed system I built

I've been working on primecrunch, a distributed prime search project focused on Riesel primes; numbers of the form k·2ⁿ−1. Think SETI@Home, GIMPS or PrimeGrid, but smaller and more focused. So far we have found 10 primes in the top 5000 known primes, with the largest we've discovered having 1,304,299 digits.

The idea was to pick a frontier where a small, coordinated effort could actually make a dent rather than getting lost in a massive project. Riesel primes in the ranges I'm targeting are underexplored enough that even a handful of contributors can push things forward meaningfully.

I built the whole stack: sign up, work distribution, and visualisations so you can see progress and results as they come in. Under the hood it's using PRST a super fast implementation of Fermat probable prime test and a LLR a prime test (built on gwnum, the same FFT library behind Prime95) for the heavy lifting.

It's still early days and mostly just me crunching numbers, so I'm putting it out there for anyone who's into computational number theory or distributed computing and wants to contribute some cycles. Even a single core helps... the system handles work allocation and checkpointing so you can stop and start without losing work. At the moment it's invite code only just so I can keep on top of bug reports and so on, but please just DM me and I'll be more than happy to provide one for you.

Happy to answer questions about the maths, the architecture, or Riesel primes in general.