The Nineteenth Byte

Pavel

8:00 PM

Ah

Anonymous

Wrong key

Pavel

Oh I see, the one you gave was 2^2^n - 1

ais523

a Mersenne number is always composite if n is composite

Anonymous

Oh duh

ETHproductions

@ConorO'Brien Each time it runs across an o it returns the number + the next item in the recursion

Conor O'Brien

8:00 PM

@ETHproductions I got an a syntax error when running this

Anonymous

I meant 2^(2^74207281 - 1) - 1

Anonymous

IOW 2^(current largest prime found) - 1

ETHproductions

@ConorO'Brien prolly the ZWNJ the SE software automatically inserts sometimes

Conor O'Brien

ohh probably

ETHproductions

Try this: for(c of s=prompt(n=o=''))c>'o'?n*=n*(n!=16):c<'i'?n &&n--:c>'i'?o+=n:n=++n-256&&n;alert(o)

Conor O'Brien

8:02 PM

that works, nice!

ETHproductions

2 bytes off: for(c of s=prompt(n=o=''))c>'o'?n*=n-16&&n:c<'i'?n &&n--:c>'i'?o+=n:n=++n-256&&n;alert(o)

Anonymous

I wonder: are there any Mersenne primes M such that 2^M - 1 isn't prime?

FlipTack

@Mego I'm pretty sure there are

Pavel

@Mego There have to be, by virtue of the fact that someone has bound to have tried it by now, and we don't have a reliable method for generating prime numbers yet, so they must have failed.

Anonymous

Then an alternate question: What is the smallest M such that 2^M - 1 is composite?

ETHproductions

8:06 PM

-2 more (I'm an idiot): for(c of prompt(n=o=''))c>'o'?n*=n-16&&n:c<'i'?n &&n--:c>'i'?o+=n:n=++n-256&&n;alert(o)

Conor O'Brien

@Mego 1

Anonymous

Alternatively: what is the smallest n such that 2^n - 1 is prime, and 2^(2^n - 1) - 1 is composite?

Pavel

@ConorO'Brien 1 isn't composite or prime

Anonymous

@ConorO'Brien M in this case being a Mersenne prime, as stated in the original question

Conor O'Brien

oh ok I misread

@Pavel I didn't see the spec originally :P

Poke

8:08 PM

This is what you do when you miss your plane. | A door in the Sky

►

Anonymous

The answer is n=13 (M=8191)

Pavel

@Mego How'd you find that? Google?

Anonymous

@Pavel Linear search with Sage

Pavel

Is Sage like Mathematica or similar?

Anonymous

Yep, but Python and free and open-source

Anonymous

8:09 PM

for n in range(15): if is_prime(2**n-1) and not is_prime(2**(2**n-1)-1): print n

Anonymous

I suppose it would be faster to do for n in Primes():

Pavel

Where Primes() an infinite generator?

That's neat

Anonymous

Sort of

Anonymous

Primes() returns a (mathematical) set object, which has .__iter__ implemented so it can yield primes like a generator

Anonymous

You can also do stuff like 5 in Primes() as an alternative to is_prime(5)

Pavel

8:14 PM

Mathematica doesn't handle mathematical sets well, it's the one weakness to it that I've found.

aditsu

@Downgoat hey is that you? i.imgur.com/c6uGJV0.gifv

2

Conor O'Brien

Try it online! (Mathematica)

Pavel

@ConorO'Brien Why mprimes := and not mprimes =

Not that it matters in this case

FlipTack

8:31 PM

Any feeback for this?

Quite an old sandbox of mine but it never got any upvotes

Mr. Xcoder

Yay just got silver number \o/

@FlipTack I don’t quite understand why truthy/falsy are used. Why not just any two distinct and consistent values?

And I think you are likely to get submissions like read from file; if empty or 0:print 0;delete contents of file; write 1; else: print 1; delete contents of file; write 0; (pseudo-code)

DJMcMayhem

8:52 PM

CMC: Logical NOT in a language where the task is not trivial

AdmBorkBork

@DJMcMayhem I'm catching you ...

New Main Posts

2

Q: Repeated Digit Primes

Another sequence, another challenge.* Definition A prime p is in this sequence, let's call it A, iff for every digit d in p's decimal expansion, you replace d with d copies of d and the resulting integer is still prime; zeros are not permitted. For example, 11 is trivially in this sequence (it...

DJMcMayhem

@AdmBorkBork Oh hush you :P

Pavel

@DJMcMayhem {<{}>(()[()])}

DJMcMayhem

@Pavel 1) That doesn't work for False inputs and 2) It's very redundant

Pavel

8:57 PM

@DJMcMayhem Oh, right, dur.

Conor O'Brien

@Pavel no clue, I don't mathematica

dzaima

@DJMcMayhem my unreleased, very unfinished stack-based ascii-art language, ０＋１α－ - ０＋ add 0 to POP which defaults to input (there's no other way to currently get input otherwise :|), １ - push 1, α get the last operators left arg - input (so add 0 could've added anything, and there's no swap top two items function :|), － - subtract that from that 1

H.PWiz

@DJMcMayhem ([{()<{}>}]{}())?

DJMcMayhem

@H.PWiz Looks right to me

Conor O'Brien

@DJMcMayhem Bf, 18 bytes: >,-[<->-]<[>+<-]>. Try it online!

H.PWiz

9:00 PM

Shorter than on the Wiki :)

Stuff that, not stack safe

DJMcMayhem

@H.PWiz Doesn't work

ninja'd

If it doesn't need to be stack clean, we could do {<>}([]{}) for 10

FlipTack

@DJMcMayhem NAND gates, A NAND A

ok actually that's probably classed as trivial

polyglot, also works with a NOR gate

Mr. Xcoder

9:17 PM

Duh.... The “sweet” taste of repcap

New Sandboxed Posts

9:34 PM

0

A: Sandbox for Proposed Challenges

Different tasks, same characters, level 2 In this challenge, you need to solve 3 different tasks using the same set of characters. You can rearrange the characters, but you can't add or remove characters. The winner will be the submission that solves all tasks using the smallest number of chara...

caird coinheringaahing

I don't care if this has been linked before in here, but I have to share this post:

22

Q: How is the taxable value of a goat determined?

I was reading an answer over on Law.SE, and it made me wonder about how the IRS calculates tax on barter transactions. Lets say that I do a job in January, and get paid for my work with 20 goats and when I received the payment, goats were worth about $100 each. Later that year, in October, I do...

united-states income-tax irs

Poke

> Sadly this means you cannot ride the goat bubble to avoid goat tax...

DJMcMayhem

@cairdcoinheringaahing Make sure that @Downgoat sees this

Poke

mac os apparently allows you to log in as root with no password twitter.com/lemiorhan/status/935578694541770752

thanks apple

DJMcMayhem

Random UI question: A dialog box asks the user to enter or select something. What would you call a popup that's like a dialog box but is just for information, rather than asking the user to do something?

Poke

9:44 PM

a popup

DJMcMayhem

There's nothing more specific than that?

Laikoni

An alert?

Poke

that's what i would call it

i suppose you could say "message dialog"

quartata

@Poke meanwhile, at literally every apple store

Poke

haha

i love that gif

Poke

10:05 PM

Anyone here use microsoft teams

caird coinheringaahing

:O Just found out that if you press the play button on Apple earpods while on chat on mobile, it makes a ping noise

Marcus Andrews

shorter way to do this either in python or ruby? (s is a string):

print((s+s[::-1])[::2])

same as every-other-letter from left to right and then the same wrapping around to the left (accounts for both even and odd)

Poke

10:22 PM

@MarcusAndrews Try it online!

Marcus Andrews

@Poke doesn't work with odd-length

Try [1, 2, 3, 4, 5]

Poke

ooo

Pavel

@Poke yes

Damn mobile chat

New Sandboxed Posts

10:56 PM

0

A: Sandbox for Proposed Challenges

418 I'm a teapot - RFC2324 code-golf, internet Rationale and Scope There is coffee all over the the world. Increasingly, in a world in which code golfing is ubiquitous, the code golfers want to make more coffee, but the conciseness of perfectly golfed, webconnected programs transcends art. T...

ATaco

11:16 PM

I'm going to give my online Funky implentation access to a Canvas.

muddyfish

11:33 PM

Dear @AppleSupport, we noticed a *HUGE* security issue at MacOS High Sierra. Anyone can login as "root" with empty password after clicking on login button several times. Are you aware of it @Apple?

Tweeted by lemiorhan on November 28, 2017 at 6:38 PM

Ouchie

Apparently I got somewhat ninja'd :3

Downgoat

11:49 PM

@cairdcoinheringaahing ಠ_ಠ goat is priceless

caird coinheringaahing

@Downgoat Well, at least people are beginning to realise that goats are the only real currency :P

Transcript for