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The Connoisseur of Number Sequences

Posted by samzenpus on from the math-man dept.

An anonymous reader writes: 75-year-old Neil Sloane is considered by many to be one of the most influential mathematicians of our time, not because of the theorems he's proved, but because of his creation: The Online Encyclopedia of Integer Sequences (OEIS). Quanta Magazine reports: "This giant repository, which celebrated its 50th anniversary last year, contains more than a quarter of a million different sequences of numbers that arise in different mathematical contexts, such as the prime numbers (2, 3, 5, 7, 11 ) or the Fibonacci sequence (0, 1, 1, 2, 3, 5, 8, 13 ). What's the greatest number of cake slices that can be made with n cuts? Look up sequence A000125 in the OEIS. How many chess positions can be created in n moves? That's sequence A048987. The number of ways to arrange n circles in a plane, with only two crossing at any given point, is A250001. That sequence just joined the collection a few months ago. So far, only its first four terms are known; if you can figure out the fifth, Sloane will want to hear from you."

63 comments

  1. A250001 by Anonymous Coward · · Score: 2, Funny

    COMMENTS a(5) reduced by 1 because of a takedown order by the IOC for their trademarked 5-ring configuration.

  2. 50th anniversary "on-line"? by tverbeek · · Score: 5, Informative

    If you're wondering how an "on-line" collection celebrated its 50th anniversary recently: the collection was begun in 1964; it was made available via the Internet starting in 1996.

    --
    http://alternatives.rzero.com/
    1. Re:50th anniversary "on-line"? by jcrb · · Score: 1

      He started collecting them in 1965, " This giant repository, which celebrated its 50th anniversary "

      --
      -jon
    2. Re:50th anniversary "on-line"? by Anonymous Coward · · Score: 0

      Well, 50 years ago it could have been stored in one of these

      https://en.wikipedia.org/wiki/IBM_1360

    3. Re:50th anniversary "on-line"? by Anonymous Coward · · Score: 0

      "This giant repository, which celebrated its 50th anniversary last year,"

      Also:
      " OEIS: Brief History
      The sequence database was begun by Neil J. A. Sloane (henceforth, "NJAS") in early 1964 ...."
      https://oeis.org/wiki/Welcome#...

      The only thing worse than a pedant is a pedantic moron.

    4. Re:50th anniversary "on-line"? by Anonymous Coward · · Score: 0

      A104175 ()
      From the words to the song "Jenny's Letterbox" by Tommy Tutone.

  3. 75-year-old Neil Sloane is considered by many by Anonymous Coward · · Score: 2, Insightful

    Who are these "many"? Horrible journalism.

    1. Re:75-year-old Neil Sloane is considered by many by Anonymous Coward · · Score: 0

      Indeed. Without any disrespect to Dr. Sloane, I had never heard of him. This may just be my own ignorance, though.

    2. Re:75-year-old Neil Sloane is considered by many by Rockoon · · Score: 2

      Who are these "many"? Horrible journalism.

      Probably talking about people like me, who have saved many hours of effort multiple times per year since discovering it over a decade ago.

      --
      "His name was James Damore."
    3. Re:75-year-old Neil Sloane is considered by many by JoshuaZ · · Score: 4, Informative

      Mathematicians. I don't how many times I've seen a sequence of integers and then gone to Sloane's encyclopedia to see if the sequence is known. This is helpful in both not duplicating others work (e.g. finding out that something one has found is already known) or b) identifying that a given sequence is a known sequence and then using that as a guideline on what to prove. That last bit happens surprisingly often when one has combinatorial structure to something: pop the sequence of numbers you've got into his database and it will tell you something like the first 6 terms matching some nice combinatorial thing and then you can with that guidance go and prove that in general that's what the sequence really is.

    4. Re:75-year-old Neil Sloane is considered by many by Gorobei · · Score: 1

      And me: I first found it as a hardcover book "a handbook of integer sequences" about 25 years ago.

    5. Re:75-year-old Neil Sloane is considered by many by plcurechax · · Score: 3, Informative

      Who are these "many"? Horrible journalism.

      Unsurprisingly, mathematicians. Many mathematicians use the OEIS frequently, heck experts and professionals from other disciplines like Computer Science, Economics, or Physics routinely use OEIS to identify numeric sequences or patterns.

      I'd hazard to say anyone who calls themselves a mathematician has used OEIS (or the book version) at least once. In fact I'd be surprised if you could find anyone with a graduate degree in mathematics who doesn't know who Neil Sloane or OEIS are.

      Yes, it is that important.

    6. Re:75-year-old Neil Sloane is considered by many by ConceptJunkie · · Score: 1

      Probably talking about people like me, who have saved many hours of effort multiple times per year since discovering it over a decade ago.

      Or people like me that often browse through the OEIS for fun, and learn lots of cool stuff from the extensive references.

      --
      You are in a maze of twisty little passages, all alike.
    7. Re:75-year-old Neil Sloane is considered by many by Anonymous Coward · · Score: 0

      I wrote a program called fundamental which does searches for formulas integer sequences of numbers it's called fundamental.
      http://www.ariasoft.ie/gplcontributions.html

    8. Re:75-year-old Neil Sloane is considered by many by Anonymous Coward · · Score: 0

      There are an infinite number of formula for any given sequence, and just finding one of them doesn't necessarily provide insight. However, finding similarities or equivalence in between sequences associated with certain processes, especially ones that have more known about them than just a formula, can lead to new ideas a lot faster.

  4. pseudo-base-prime by orangesquid · · Score: 1

    OEIS is great. I started working on a project and was able to find some other work done on the same sequence(s)... ,3,5,9,7,15,11,27,... -- my project concerns representing the positive integers in terms of their prime factorization and then examining the properties of various operations on this representation. =)

    --
    --TheOrangeSquid Is it any wonder things seem so awry? We swim in a sea of confusion and don't have to think to survive
    1. Re:pseudo-base-prime by Applehu+Akbar · · Score: 1

      Any of you old timers remember the Chemical Rubber Handbook? It's a site now also:
      http://www.hbcpnetbase.com/

    2. Re:pseudo-base-prime by Fortran+IV · · Score: 1

      I still refer regularly to my CRC Standard Math Tables—two different editions, both sadly decades out of date.

      I was tickled years ago to discover the OEIS; some other math website referred to it, and I was lost for hours. TV Tropes for math nerds.

      --
      I figure by 2030 or so my 6-digit UID will be something to brag about.
  5. One of the worst words in the english language by Racemaniac · · Score: 0

    Maybe it's because i also speak french (but neither english nor french are my native language), but connoisseur.... wtf. When i first heard it used in Futurama, i actually thought it was a small joke of an english speaker completely mispronouncing a french (connaisseur) word, trying to sound smarter than he was, but it's an actual english word 0_0. I cringe every time i hear or read it.

    1. Re:One of the worst words in the english language by Anonymous Coward · · Score: 0

      I cringe every time i hear or read it.

      English has its fair number of mistransliterated words. However, this one is intentional, and a grand success based on your comment.

    2. Re:One of the worst words in the english language by Anonymous Coward · · Score: 0

      And, according to Wikipedia, it's English that retained the traditional spelling.

    3. Re:One of the worst words in the english language by Anonymous Coward · · Score: 2, Insightful

      Actually "connoisseur" was the correct French spelling when English borrowed it, and later the French spelling was changed. Racemaniac should study his native language a little bit more before pointing fingers.

    4. Re:One of the worst words in the english language by Anonymous Coward · · Score: 1

      That was actually the correct French spelling at the time when it was borrowed into the English language.

    5. Re:One of the worst words in the english language by Anonymous Coward · · Score: 0

      Why do you think that? It's a cromulent English word with its root in old french, "connoistre", which means "to be acquainted with".

    6. Re:One of the worst words in the english language by Anonymous Coward · · Score: 0

      I don't know how you have heard people pronounce it, though.

      The correct English pronunciation is more or less the same as the correct French pronunciation. About as close as you can get given the phonological differences between the two languages, at least.

    7. Re:One of the worst words in the english language by Paradise+Pete · · Score: 1

      He didn't even say what his native language is, so we can hardly know if studying it would help his French.

    8. Re:One of the worst words in the english language by khallow · · Score: 2

      You do realize that the French language has changed the spelling of many of its words over the centuries? Glancing through the online dictionaries, it appears the word "connoisseur" entered the English language around the beginning of the 18th century, 300 years ago. And there's some French words that came over with William the Conqueror almost a millennium ago.

    9. Re:One of the worst words in the english language by Guy+Harris · · Score: 1

      He didn't even say what his native language is, so we can hardly know if studying it would help his French.

      He did say what it wasn't - "(but neither english nor french are my native language)". So presumably it would help his French only if it were sufficiently closely related to French.

    10. Re:One of the worst words in the english language by Paradise+Pete · · Score: 1

      Yes, I was attempting to sarcastically point out that the poster's criticism was based on misunderstanding what he was criticizing.

  6. Numbers by justthinkit · · Score: 0

    They are numbers. Big ones. Small ones. Numbers that repeat themselves into bigger numbers. Number with zeroes and numbers with ones. Numbers for young and old. Many, many numbers!

    Password numbers and briefcase numbers. Hot date and credit card collection numbers. Your weight last year and your weight now :-( numbers.

    Your salary number and your worth number. Your debt number and your empty pocket number.

    How much you will inherit and how much you actually got.

    And so on.

    I would have thought it was obvious who they were.

    --
    I come here for the love
    1. Re:Numbers by Anonymous Coward · · Score: 0

      Numbers don't consider, except for Number Six.

  7. A Cinco Product. by xenotransplant · · Score: 2

    Encyclopedia of Numbers

  8. I thought this was America by PopeRatzo · · Score: 1

    If Neil Sloane is so smart, why ain't he rich?

    Let me know when his list includes the number sequence for tomorrow's Lotto.

    --
    You are welcome on my lawn.
    1. Re:I thought this was America by fropenn · · Score: 1

      I'm sure it's in there somewhere. You just have to know where to look.

    2. Re:I thought this was America by xfade551 · · Score: 1

      If Neil Sloane is so smart, why ain't he rich?

      Let's see, they say that "Knowledge is Power", so knowledge = power, and we know from physics that power = work / time. And finally, they say that "Time is money", so time = money.

      So, making the substitutions: knowledge = work / money, and solving for money, money = work / knowledge.

      So, now we can see that the dumber you are, the more money you can make!

    3. Re:I thought this was America by MagickalMyst · · Score: 1

      "So, now we can see that the dumber you are, the more money you can make!"

      i.e; the mafia, Dubya, Brittany Spears, etc.

      An explanation.

      --
      Political correctness is really just herd psychology pushed by insecure people who desperately seek social conformity.
    4. Re:I thought this was America by mattack2 · · Score: 1

      "So, now we can see that the dumber you are, the more money you can make!"

      i.e; the mafia, Dubya, Brittany Spears, etc.

      So says someone who uses "i.e." when the proper term in this case is "e.g."

    5. Re:I thought this was America by david_thornley · · Score: 1

      Don't come down on him; he obviously is angling for a raise.

      --
      "When you have eliminated the unacceptable, whatever is left, however improbable, must be the truthiness" - Holmes
  9. Before there was the interwebs by jcrb · · Score: 1

    There was the HandBOOK of Integer Sequences.
    Some of my math professors are probably still wondering how I solved those extra credit problems :)
    It was good for party tricks are well, at the right sort of party obviously.

    --
    -jon
  10. fir5T. by Anonymous Coward · · Score: -1

    the future holds propaganda and and the striking Of challenges that brilliant plan too much formality Developers. The fun to be again. beyond the scope 0f gig in front of is the ultimate the reaper BSD's all servers. Coming to yet another for the project. Problems with surveys show that and/or distribute It simple, forwards we must previously thought FreeBSD because

  11. I am SO surprised that he isn't African... by Anonymous Coward · · Score: -1

    Or even Australian 'aborigine', what with 'us all being the same', and the average IQ of an African not being 70, or anything terrible like that...

    1. Re:I am SO surprised that he isn't African... by Anonymous Coward · · Score: -1

      Aren't you supposed to be buggering some little aboriginal boy's ass, what with just about every person who brings their IQ up usually some freak who's into gay interspecies sex trying to justify their attractions by declaring that they're subhuman?

  12. Elevator sequence by glitch! · · Score: 4, Funny

    I like the sequence: 1,2,1,1,1,1 ...

    The X axis is the number of people in an elevator.
    The Y axis is how many people know which one farted.

    --
    A dingo ate my sig...
    1. Re:Elevator sequence by Anonymous Coward · · Score: 0

      Dammit man, ya left off S[0].

      You're also simplifying the problem. What if I take an early lunch and return from Taco Bell just before noon, get on elevator #1 in the lobby, press 6, drop a few liters of foulness, get off, and use elevator #2 to return just in time to witness the first victims enter "the gas chamber" (TM).

    2. Re:Elevator sequence by Anonymous Coward · · Score: 0

      Just make sure you're not seen carrying a Taco Bell cup, or they'll know it was you.

  13. Do they have... by JFMulder · · Score: 1

    1 - 2 - 3 - 4 - 5, which is commonly used for luggage combinations and planetary shields?

    1. Re:Do they have... by Garfong · · Score: 1

      Yes, that's A000027.

    2. Re:Do they have... by TeknoHog · · Score: 1

      000027? That's the combination to my luggage!

      --
      Escher was the first MC and Giger invented the HR department.
    3. Re:Do they have... by ConceptJunkie · · Score: 1

      I spent weeks writing a program to expand that list to 1000 items and oeis.org wouldn't accept it.

      Snobs.

      --
      You are in a maze of twisty little passages, all alike.
  14. Cool Homework Helper by Anonymous Coward · · Score: 0

    When the kids bring home problems that say "What's the next number in this sequence, ..." they can just plug in the numbers and voila.

  15. More practical application ... by UnknownSoldier · · Score: 1

    ... as a practice exercise for optimization.

    Mike Acton gave an excellent talk Code Clinic 2015: How to Write Code the Compiler Can Actually Optimize where he picked an integer sequence to optimize the run-time to calculate the sequence. Techniques include: memoization, and common sub-term recognition. For 20 values pre-optimization time was: 31 seconds, post-optimization time was: 0.01 seconds.

    * https://youtu.be/GPpD4BBtA1Y?t...

    Original GDC Talk

    * http://gdcvault.com/play/10218...

  16. The pissing sequence by Anonymous Coward · · Score: 0

    A095236 is about pay phones, but in the modern era, it is something that males could relate to when choosing a urinal.

  17. AUTOMATIC LEAD TOOLS IS BEST FOR BUSINESS by boboyd · · Score: -1

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    1. Re:AUTOMATIC LEAD TOOLS IS BEST FOR BUSINESS by Guy+Harris · · Score: 1

      AUTOMATIC LEAD TOOLS IS BEST FOR BUSINESS

      Actually, most tools have to be made from harder metals than lead.

    2. Re:AUTOMATIC LEAD TOOLS IS BEST FOR BUSINESS by Anonymous Coward · · Score: 0

      Also, don't forget to ask for Jenny for our special discount. 867 5309!

    3. Re:AUTOMATIC LEAD TOOLS IS BEST FOR BUSINESS by Anonymous Coward · · Score: 0

      Automatic lead tools are de facto banned in the US unless you're rich. That said, they work just fine without using a harder metal, though I hear DU is in style some places.

    4. Re:AUTOMATIC LEAD TOOLS IS BEST FOR BUSINESS by neminem · · Score: 1

      Ugh, I actually worked with LeadTools at work a few years ago, it was a pain. We had to rip out all the calls to a previous imaging library because they'd changed their licensing terms to one upper management didn't like... then after I'd replaced everything with calls to LeadTools, it came down that upper management didn't like their terms anyway, and we were going to end up building our own. Which was fine by me, anyway, LeadTools' API is kinda mediocre.

      Not sure what that has to do with working from home, though.

  18. Re: Handbooks by plcurechax · · Score: 2

    Any of you old timers remember the Chemical Rubber Handbook? It's a site now also:
    http://www.hbcpnetbase.com/

    I admit I've always heard it called the CRC Handbook(s). The "original" being their Chemistry and Physics one (the one at the link), though CRC Press does tons of technical, scientific printing in the US, they also have handbooks on topics in computer science, computer security and many others.

    And my copy is I think 80-something-th edition.

  19. Number of arrangements of n circles... by tlambert · · Score: 1

    Number of arrangements of n circles in the affine plane:

    1, 1, 3, 14, 168, ...

    If anyone cares, the next number in this sequence is 3172. And no, I did not brute force it, I examined the problem symmetry.

    1. Re:Number of arrangements of n circles... by lyran74 · · Score: 1

      Care to share your work?

    2. Re:Number of arrangements of n circles... by tlambert · · Score: 1

      You mean like that the next value after that is 91958?

      And the one after that 3402408?

      }B^)

    3. Re:Number of arrangements of n circles... by lyran74 · · Score: 1

      Like your high school math teacher would, I give you a grade of zero for those answers.

    4. Re:Number of arrangements of n circles... by tlambert · · Score: 1

      Yes, I understood that you were implying that you wanted:

      (1) A description of the realization
      (2) The process by which I arrived at the realization ("show your work")
      (3) A description of the algorithm, process, or formula used to obtain the next number in the sequence given the previous numbers as a clue

      Why don't we wait for brute force verification as to whether or not I'm correct, shall we? If that verification happens, I will happily describe those three points, and ruin a perfectly good (so far) crypto algorithm for everyone.