Zahlen, bitte! OEIS – Encyclopedia for number nerds

Contents

For anyone who deals with number sequences, the Online Encyclopedia of Integer Sequences is the most important search engine in the world. It is the work of the British-Australian mathematician Neil Sloane, who created this encyclopedia 60 years ago with a small collection of index cards.

Zahlen, bitte!

In this section, we present amazing, impressive, informative and funny figures ("Zahlen") from the fields of IT, science, art, business, politics and, of course, mathematics every Tuesday. The wordplay "Zahlen, bitte!" for a section about numbers is based on the ambiguity of the German word "Zahlen." On one hand, "Zahlen" can be understood as a noun in the sense of digits and numerical values, which fits the theme of the section. On the other hand, the phrase "Zahlen, bitte!" is reminiscent of a waiter's request in a restaurant or bar when they are asked to bring the bill. Through this association, the section acquires a playful and slightly humorous undertone that catches the readers' attention and makes them curious about the presented numbers and facts.

• Alle Artikel zu "Zahlen, bitte!"

In October 2024, Sloane will be 85 years old and will be able to look back on 376,574 entries in his online encyclopedia that came to digital life 30 years ago with 16,000 entries as an email service, having previously been available as a book – completely analog –

First book published in 1973

The other numbers in the title refer to the analog pre-life of the sequences: the first book edition "A Handbook of Integer Sequences" was published in 1973 with 2373 entries collected by Sloane, and in 1995 Sloane published "The Encyclopedia of Integer Sequences" with 5488 entries together with the Canadian mathematician Simon Plouffe.

Some of the authors of this column have dealt with number sequences that can be found in the Online Encyclopedia of Integer Sequences , such as Andreas Stiller in his search for the perfect numbers.

Volker Zota used the OEIS to see whether the 73 is the "Chuck Norris of the number universe". There are number sequences that lead to philosophical questions, such as when pondering the entry A0138563 searching for the devil's fax number. Yes, it's true: Faxes are sometimes hell – but how can a fax survive in hell?

Less useful are chess problems such as the maximum number of queens that can be placed on a three-dimensional chessboard without threatening each other (A068940). There are entries with one or two hints, but also those such as A000045 on the famous Fibonacci numbers, which open up a whole mathematical universe.

Well-stocked department store of numbers

Because Sloane spent his entire professional life at Bell Labs or AT&T Labs in New Jersey, number sequences from New York subways such as A00053 are among the earliest entries in the encyclopedia. Opinions differ: one German reviewer called the OEIS a huge, well-stocked "numbers department store",

In France, Sloane's project was praised as a database in the tradition of the OuLiPo project by mathematician François Le Lionnais and writer Raymond Queneau. In the USA, Sloane is presented as a number cruncher, the opposite of Chuck Norris, so to speak.

The creation and development of Neil Sloane's OEIS is closely linked to information technology. As a student in 1963, Sloane dealt with number sequences such as 0, 1, 8, 78, 944, 13,800, 237,432 as part of his dissertation "Lenghts of Cycle Time in Random Neural Networks" and wanted to search for similar number sequences in the technical literature.

In the beginning there were index cards

He discovered that nobody had dealt with this question, and from 1964 onwards, he started a small collection of index cards, the first entry of which was his own number problem. When he started working at Bell Labs, the collection first went onto punch cards, then onto magnetic tapes and finally onto the Internet, first by e-mail, then as a website. Sloane added around 170,000 entries himself.

Today, the OEIS is a wiki and is maintained by around 100 volunteers, with Sloane as the final authority on disputed decisions. Up to 30 suggestions a day from number enthusiasts want to be processed. The new figures come from mathematics, physics, chemistry and many other fields and are submitted by researchers and amateurs in the respective area.

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Some are rejected, such as the page numbers of all the Harry Potter books (PDF) – even nerds sometimes know their limits. But some things are also presented by Sloane in the podcast Numberphile, including background music – because the number sequences of the OEIS can be played.

Of course, the entry A001337 – similar to the start time of almost all numbers, please! – is of particular interest. It deals with the face-centered cubic Bravais lattice of crystals and thus refers to the research of Neil Sloane, who worked on error-correcting codes and the Kuss number problem at AT&T Labs. Just like Mr. Spock, another number fanatic, we wish Sloane peace and a long life and that his lively mind can pursue many more interesting numbers.

(mki)