[HN Gopher] The On-Line Encyclopedia of Integer Sequences
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The On-Line Encyclopedia of Integer Sequences
Author : pseudolus
Score : 150 points
Date : 2021-04-17 23:57 UTC (23 hours ago)
(HTM) web link (oeis.org)
(TXT) w3m dump (oeis.org)
| kingsuper20 wrote:
| I suggest a mega-CISC architecture where all of those sequences
| are represented by an opcode.
| dang wrote:
| If curious, past threads:
|
| _The On-Line Encyclopedia of Integer Sequences_ -
| https://news.ycombinator.com/item?id=21366618 - Oct 2019 (28
| comments)
|
| _The online encyclopaedia of integer sequences_ -
| https://news.ycombinator.com/item?id=18524115 - Nov 2018 (3
| comments)
|
| _The On-Line Encyclopedia of Integer Sequences [pdf]_ -
| https://news.ycombinator.com/item?id=18015493 - Sept 2018 (4
| comments)
|
| _The On-Line Encyclopedia of Integer Sequences_ -
| https://news.ycombinator.com/item?id=15900294 - Dec 2017 (1
| comment)
|
| _Pictures from the On-Line Encyclopedia of Integer Sequences_ -
| https://news.ycombinator.com/item?id=11711212 - May 2016 (5
| comments)
|
| _The Surprising Power of Neil Sloane's Encyclopedia of Integer
| Sequences_ - https://news.ycombinator.com/item?id=10435690 - Oct
| 2015 (7 comments)
|
| _The On-Line Encyclopedia of Integer Sequences_ -
| https://news.ycombinator.com/item?id=9919535 - July 2015 (19
| comments)
|
| _Neil Sloane: the man who loved only integer sequences_ -
| https://news.ycombinator.com/item?id=9380292 - April 2015 (2
| comments)
|
| _The On-Line Encyclopedia of Integer Sequences_ -
| https://news.ycombinator.com/item?id=6650490 - Oct 2013 (20
| comments)
|
| _The On-Line Encyclopedia of Integer Sequences_ -
| https://news.ycombinator.com/item?id=2496629 - April 2011 (7
| comments)
|
| _The On-Line Encyclopedia of Integer Sequences_ -
| https://news.ycombinator.com/item?id=888577 - Oct 2009 (2
| comments)
|
| I thought there were larger ones...perhaps somebody will find
| one.
| surfsvammel wrote:
| This is great for Advent of Code:)
| forgotpwd16 wrote:
| There're few times some well-known sequences have appeared in
| AoC. Examples are Manhattan distances (OEIS:A214526) and square
| sums spiral (OEIS:A141481) in 2017d3, tribonacci (OEIS:A000073)
| in 2020d10, and Van Eck's sequence (OEIS:A181391) in 2020d15.
| bear8642 wrote:
| Thanks for reminding me of this.
|
| It's very useful identifying known patterns and also discovering
| new patterns by entering random number strings
| alufers wrote:
| I like how everybody here uses this website for some profound
| mathematical purposes, but I once won a cordless drill due to the
| OEIS in high school. At some hackathon Bosh had a booth with a
| contest where you had to solve puzzles which consiststed mainly
| of finishing integer sequences. I remembered this encyclopedia
| and I found all of them on the oeis.
| YetAnotherNick wrote:
| It is regularly used in coding contests too where some hard
| challenge can sometimes be found out to be some maths formula.
| FabHK wrote:
| Yeah, OEIS also helps with quite a few Project Euler
| problems.
|
| https://projecteuler.net
| quakeguy wrote:
| Good article about Sloane here:
|
| https://www.theguardian.com/science/alexs-adventures-in-numb...
| mnbv55 wrote:
| One of the best websites on the internet.
| roenxi wrote:
| https://oeis.org/A27
|
| Looking at the URL, they got 26 sequences in (including the 0
| sequence) before someone added the counting numbers.
| thuum7 wrote:
| Neil Sloane on Numberphile
| https://youtube.com/playlist?list=PLt5AfwLFPxWJXQqPe_llzWmTH...
| imglorp wrote:
| Neil's got his own channel and just posted an accessible talk
| about cellular automata and other open problems. He could use
| some views!
|
| https://www.youtube.com/watch?v=9ogbsh8KuEM
| uyt wrote:
| Has there been any progress on https://www.kaggle.com/c/integer-
| sequence-learning?
| lifthrasiir wrote:
| There is also an attempt [1] to collect and (largely)
| synthesize a program for every OEIS sequence in an
| intentionally constrained DSL.
|
| [1] https://github.com/ckrause/loda
| forgotpwd16 wrote:
| >In total, there are currently more than 26,000 programs
| available
|
| Wow, lot of work has gone to it. Why the decision to utilize
| an assembly language?
| lifthrasiir wrote:
| As far as I can tell its assembly language is designed for
| fast synthesis and check (e.g. all programs are known to
| terminate). There is a "miner" generating programs and
| checking against existing sequences 24/7, a Twitter bot is
| also available [1].
|
| [1] https://twitter.com/lodaminer
| glangdale wrote:
| Thanks for this link. I am working on a superoptimizer and
| once had the thought that OEIS would be a cool place to look
| for workloads. It's gratifying that someone else is doing
| this and having some success.
| ColinWright wrote:
| I've been involved in a few of these sequences. The most recent
| is this one:
|
| https://oeis.org/A294249
|
| My early calculations have been superseded so I'm no longer
| mentioned, but I was involved in the initial calculations for
| this sequence:
|
| https://oeis.org/A013998
|
| It's an interesting and useful project. Any time you have a thing
| you don't understand it's worth finding some way of converting it
| to an integer sequence and then looking it up, just in case.
| svat wrote:
| The best description of the OEIS I've heard is by Donald Knuth in
| this fun talk (https://youtu.be/BxQw4CdxLr8) where at 19:50 he
| says how it lets you "compute your way into the literature":
|
| > _For the last 30 years or more, there has been a wonderful tool
| for all kinds of problems of this form and it 's been online for
| a long time: we have the Online Encyclopedia of Integer
| Sequences. And this is just the nicest thing since sliced bread
| for mathematics because you can compute your way into the
| literature. [audience laughter] If you want to know if anybody
| else has ever studied a problem, all you have to do is evaluate
| the first few cases of it and then you look it up and there it
| is. The hit rate is incredible, and all kinds of mathematicians
| have discovered each other through the OEIS._ [...] _I donate to
| Wikipedia and the Internet Archive and the OEIS._
|
| (Aside: A good blog post about that lecture:
| https://thenewstack.io/donald-knuths-christmas-tree-lecture-...)
|
| Indeed I've used it this way many times; the most recent example
| is that I became curious about how many polynomial functions
| there are mod n (after posting this comment:
| https://news.ycombinator.com/item?id=26482028), and by computing
| the answers for n up to 10, I was able to look up up those
| numbers in the OEIS and find the general formula, and also the
| relevant papers. (Asked a question about it here:
| https://math.stackexchange.com/questions/4070051/how-many-di...
| but ended up answering it myself...) I don't think I'd have even
| known where to look (as I'm not a professional mathematician), if
| not for the OEIS. And this happens again and again.
| bjoli wrote:
| I have answered more than a few "what does this code do?" by
| just doing that.
|
| Feed the code some numbers, look for the output in oeis and
| bam! Instant guru status.
| glangdale wrote:
| Always great. A fine technique to compensate for those of us who
| lack mathematical sophistication: write some godawful brute force
| code to calculate the number of items in some construct of
| interest, then search those numbers up to learn all sorts of
| useful new things about what you have.
|
| I learned about generalizations of the Fibonacci sequence and
| "half-Catalan numbers" by this method.
| RockofStrength wrote:
| The OEIS can also be considered a sort of number encyclopedia,
| especially for large numbers.
|
| It can also be interesting to link geometric observations with
| unrelated OEIS sequences. For example, the number of rectangles
| on a square grid turned out to be the octagonal pyramidal
| numbers.
| nickdrozd wrote:
| The OEIS is an amazing tool. I recently came across a sequence
| from an unusual source and then made the shocking discovery that
| the sequence already existed. It turned out to be a wild
| coincidence.
|
| Write-up here: https://nickdrozd.github.io/2021/04/12/math-fact-
| busy-beaver...
| applecrazy wrote:
| The OEIS is so useful when I have some sequence and I have no
| clue how to efficiently implement it in code.
|
| More often than not, there's a formula to generate the ith term
| in the sequence in close to O(1) time.
| Bostonian wrote:
| What programming language are the sequences coded in? Is the code
| available?
| ColinWright wrote:
| The sequences are listed, and in each entry there are usually
| examples given of how to compute the sequence in multiple
| programming languages.
| fdiskl wrote:
| I love this site. Often if I solve a Project Euler problem of the
| form "what is the xth element...", after I solve it, I will look
| at the first several elements in the sequence and start seeing
| where else the sequence is used.
| tshaddox wrote:
| I like the self-referential sequences, like "Numbers n such that
| OEIS sequence A_n contains n." https://oeis.org/A053873
| tromp wrote:
| I like the closely related "Numbers n such that OEIS sequence
| A_n doesn't contain n."
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(page generated 2021-04-18 23:03 UTC)