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Upcoming Changes to Let's Encrypt Certificates

https://community.letsencrypt.org/t/upcoming-changes-to-let-s-encrypt-certificates/243873
128•schmuckonwheels•2h ago•76 comments

Umbrel – Personal Cloud

https://umbrel.com
88•oldfuture•2h ago•48 comments

Essential Semiconductor Physics [pdf]

https://nanohub.org/resources/43623/download/Essential_Semiconductor_Physics.pdf
56•akshatjiwan•2d ago•3 comments

A kernel bug froze my machine: Debugging an async-profiler deadlock

https://questdb.com/blog/async-profiler-kernel-bug/
16•bluestreak•1h ago•5 comments

“Super secure” messaging app leaks everyone's phone number

https://ericdaigle.ca/posts/super-secure-maga-messaging-app-leaks-everyones-phone-number/
407•e_daigle•2h ago•165 comments

Cosmic-ray bath in a past supernova gives birth to Earth-like planets

https://www.science.org/doi/10.1126/sciadv.adx7892
65•toomuchtodo•5h ago•19 comments

US TikTok investors in limbo as deal set to be delayed again

https://www.bbc.com/news/articles/cp34442z25ko
120•1659447091•2d ago•55 comments

Chafa: Terminal Graphics for the 21st Century

https://hpjansson.org/chafa/
55•birdculture•3h ago•5 comments

Ford kills the All-Electric F-150

https://www.wired.com/story/ford-kills-electric-f-150-lightning-for-hybrid/
32•sacred-rat•23m ago•19 comments

“Are you the one?” is free money

https://blog.owenlacey.dev/posts/are-you-the-one-is-free-money/
15•samwho•3d ago•2 comments

Avoid UUID Version 4 Primary Keys in Postgres

https://andyatkinson.com/avoid-uuid-version-4-primary-keys
317•pil0u•12h ago•324 comments

Carrier Landing in Top Gun for the NES

https://relaxing.run/blag/posts/top-gun-landing/
331•todsacerdoti•7h ago•131 comments

It seems that OpenAI is scraping [certificate transparency] logs

https://benjojo.co.uk/u/benjojo/h/Gxy2qrCkn1Y327Y6D3
172•pavel_lishin•8h ago•91 comments

We are discontinuing the dark web report

https://support.google.com/websearch/answer/16767242?hl=en
52•satertek•7h ago•22 comments

I'm Kenyan. I don't write like ChatGPT, ChatGPT writes like me

https://marcusolang.substack.com/p/im-kenyan-i-dont-write-like-chatgpt
428•florian_s•9h ago•289 comments

Problems with D-Bus on the Linux desktop

https://blog.vaxry.net/articles/2025-dbusSucks
233•LorenDB•3h ago•142 comments

Liquid-rust: Liquid templating for Rust

https://github.com/cobalt-org/liquid-rust
10•transpute•5d ago•5 comments

We architected an edge caching layer to eliminate cold starts

https://www.mintlify.com/blog/page-speed-improvements
24•skeptrune•6h ago•15 comments

The appropriate amount of effort is zero

https://expandingawareness.org/blog/the-appropriate-amount-of-effort-is-zero/
11•gmays•2h ago•2 comments

I used Claude Code to write a piano web app

https://jcurcioconsulting.com/posts/how-i-used-claude-code-to-write-a-piano-web-app
3•Jeremy1026•1h ago•0 comments

Optery (YC W22) Hiring CISO, Release Manager, Tech Lead (Node), Full Stack Eng

https://www.optery.com/careers/
1•beyondd•10h ago

Building an efficient hash table in Java

https://bluuewhale.github.io/posts/building-a-fast-and-memory-efficient-hash-table-in-java-by-bor...
63•birdculture•2d ago•7 comments

US Tech Force

https://techforce.gov/
141•purple_ferret•4h ago•180 comments

Show HN: I Ching simulator with accurate Yarrow Stalk probabilities

https://castiching.com/
44•jackzhuo•1d ago•28 comments

Show HN: A pager

https://www.udp7777.com/
71•keepamovin•1d ago•28 comments

Ask HN: What Are You Working On? (December 2025)

377•david927•1d ago•1251 comments

SoundCloud has banned VPN access

https://old.reddit.com/r/SoundCloudMusic/comments/1pltd19/soundcloud_just_banned_vpn_access/
239•empressplay•19h ago•164 comments

AI agents are starting to eat SaaS

https://martinalderson.com/posts/ai-agents-are-starting-to-eat-saas/
341•jnord•22h ago•343 comments

Ask HN: Is building a calm, non-gamified learning app a mistake?

58•hussein-khalil•6h ago•89 comments

Adafruit: Arduino’s Rules Are ‘Incompatible With Open Source’

https://thenewstack.io/adafruit-arduinos-rules-are-incompatible-with-open-source/
409•MilnerRoute•1d ago•221 comments
Open in hackernews

Right-Truncatable Prime Counter

https://github.com/EbodShojaei/Right-Truncatable-Primes
9•rainmans•6mo ago

Comments

throwawaymaths•6mo ago
Curious about base 2. Obviously if you hit a 0 it's immediately not prime, but maybe adjust the rules so:

- you drill through as many 0's on the right.

- you finish on 1.

3, 5, 7, 11, 13, 15, 17 are all right truncatable, 19 is the first non-truncatable prime in this scheme.

nh23423fefe•6mo ago
i dont think smaller radixes make the problem more interesting. the problem is interesting because base 10 has a large branching factor
throwawaymaths•6mo ago
I think in the base2 reformulation I propose we do not know for certain if the list of numbers terminates, as all Fermat primes are in the set and we don't know if there are infinitely many Fermat primes.

For base-10 and the original rules the set is provably closed.

"Drilling through zeros" makes the branching unbounded.

jinwoo68•6mo ago
There's a Project Euler problem for finding truncatable prime numbers, from both left and right: https://projecteuler.net/problem=37
thechao•6mo ago
Just in case any else is wondering: there are only 83 right-truncatable primes (RTP) and that is it. There's two constraints that let you see this "immediately":

1. An RTP must start with {2,3,5,7,9}; and,

2. An RTP must end with {1,3,7,9}.

So, let's take the largest RTP (73939133) and try to "extend" it: there are only four possible extensions: 73939133[1], 73939133[3], 73939133[7], 73939133[9]. None of these are prime. This holds for the other 8-digit RTPs. Therefore, there is no extension to a 9-or-longer RTP. Thus, the list is exhaustive.