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NIST scientists create 'any wavelength' lasers

https://www.nist.gov/news-events/news/2026/04/any-color-you-nist-scientists-create-any-wavelength...

168•rbanffy•5h ago•75 comments

Anonymous request-token comparisons from Opus 4.6 and Opus 4.7

https://tokens.billchambers.me/leaderboard

428•anabranch•9h ago•428 comments

The electromechanical angle computer inside the B-52 bomber's star tracker

https://www.righto.com/2026/04/B-52-star-tracker-angle-computer.html

273•NelsonMinar•9h ago•79 comments

College instructor turns to typewriters to curb AI-written work

https://sentinelcolorado.com/uncategorized/a-college-instructor-turns-to-typewriters-to-curb-ai-w...

137•gnabgib•6h ago•140 comments

Modern Common Lisp with FSet

https://fset.common-lisp.dev/Modern-CL/Top_html/index.html

88•larve•3d ago•7 comments

Updating Gun Rocket through 10 years of Unity Engine

https://jackpritz.com/blog/updating-gun-rocket-through-10-years-of-unity-engine

8•tyleo•2d ago•0 comments

Why Japan has such good railways

https://worksinprogress.co/issue/why-japan-has-such-good-railways/

310•RickJWagner•13h ago•310 comments

Optimizing Ruby Path Methods

https://byroot.github.io/ruby/performance/2026/04/18/faster-paths.html

52•weaksauce•5h ago•20 comments

Migrating from DigitalOcean to Hetzner

https://isayeter.com/posts/digitalocean-to-hetzner-migration/

682•yusufusta•12h ago•350 comments

State of Kdenlive

https://kdenlive.org/news/2026/state-2026/

335•f_r_d•14h ago•112 comments

Thoughts and feelings around Claude Design

https://samhenri.gold/blog/20260418-claude-design/

233•cdrnsf•6h ago•155 comments

NASA Shuts Off Instrument on Voyager 1 to Keep Spacecraft Operating

https://science.nasa.gov/blogs/voyager/2026/04/17/nasa-shuts-off-instrument-on-voyager-1-to-keep-...

64•sohkamyung•2h ago•24 comments

Dad brains: How fatherhood rewires the male mind

https://www.bbc.com/future/article/20260417-fatherhood-how-the-male-brain-and-body-prepare-for-ch...

72•tchalla•3h ago•32 comments

Zero-Copy GPU Inference from WebAssembly on Apple Silicon

https://abacusnoir.com/2026/04/18/zero-copy-gpu-inference-from-webassembly-on-apple-silicon/

14•agambrahma•3h ago•8 comments

Michael Rabin has died

https://en.wikipedia.org/wiki/Michael_O._Rabin

387•tkhattra•3d ago•81 comments

Show HN: MDV – a Markdown superset for docs, dashboards, and slides with data

https://github.com/drasimwagan/mdv

94•drasim•10h ago•34 comments

Sumida Aquarium Posts 2026 Penguin Relationship Chart, with Drama and Breakups

https://www.sumida-aquarium.com/special/sokanzu/en/2026/

166•Lwrless•3d ago•5 comments

My first impressions on ROCm and Strix Halo

https://blog.marcoinacio.com/posts/my-first-impressions-rocm-strix-halo/

16•random_•4h ago•1 comments

A story about how I dug into the PostgreSQL sources to write my own WAL receiver

https://medium.com/@mailbox.sq7/a-long-story-about-how-i-dug-into-the-postgresql-source-code-to-w...

20•alzhi7•22h ago•2 comments

Scientists discover “cleaner ants” that groom giant ants in Arizona desert

https://www.sciencedaily.com/releases/2026/04/260414075641.htm

79•t-3•3d ago•28 comments

Floating Point Fun on Cortex-M Processors

https://danielmangum.com/posts/floating-point-cortex-m/

39•hasheddan•1d ago•1 comments

PgQue: Zero-Bloat Postgres Queue

https://github.com/NikolayS/pgque

86•gmcabrita•9h ago•12 comments

Understanding the FFT Algorithm (2013)

https://jakevdp.github.io/blog/2013/08/28/understanding-the-fft/

64•peter_d_sherman•3d ago•6 comments

UpCodes (YC S17) is hiring SDRs to help make construction more productive

https://up.codes/careers?utm_source=HN

1•Old_Thrashbarg•8h ago

80386 Memory Pipeline

https://nand2mario.github.io/posts/2026/80386_memory_pipeline/

89•wicket•4d ago•12 comments

Amiga Graphics Archive

https://amiga.lychesis.net/

232•sph•19h ago•73 comments

Show HN: SmallDocs – Markdown without the frustrations

56•FailMore•3d ago•24 comments

Fuzix OS

https://www.fuzix.org/

76•DeathArrow•10h ago•25 comments

Brunost: The Nynorsk Programming Language

https://lindbakk.com/blog/introducing-brunost

133•atomfinger•5d ago•72 comments

Category Theory Illustrated – Orders

https://abuseofnotation.github.io/category-theory-illustrated/04_order/

231•boris_m•19h ago•59 comments

Open in hackernews

Right-Truncatable Prime Counter

https://github.com/EbodShojaei/Right-Truncatable-Primes

9•rainmans•10mo ago

Comments

throwawaymaths•10mo 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•10mo ago

i dont think smaller radixes make the problem more interesting. the problem is interesting because base 10 has a large branching factor

throwawaymaths•10mo 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•10mo ago

There's a Project Euler problem for finding truncatable prime numbers, from both left and right: https://projecteuler.net/problem=37

thechao•10mo 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.