411 REFERENCE · Wiktionary
Farey sequence
Reference material by Wiktionary contributors. This retains its source identity and is not 411 news reporting.
English
Etymology
Named after British geologist John Farey Sr., whose letter about the sequences was published in the Philosophical Magazine in 1816.
Noun
en number theory For a given positive integer n, the sequence of completely reduced fractions between 0 and 1 which, when in lowest terms, have denominators less than or equal to n, arranged in order of increasing size.
en 2002 Alfred S. Posamentier; Jay Stepelman Teaching Secondary Mathematics Merrill https://books.google.com.au/books?id=giZMAAAAYAAJ&q=%22Farey+sequence%22%7C%22Farey+sequences%22&dq=%22Farey+sequence%22%7C%22Farey+sequences%22&hl=en&sa=X&ved=2ahUKEwiSrNC1vKLrAhUHX30KHT_1B00Q6AEwDnoECDUQAg 403 Students should then see the number of fractions , in the Farey sequence is equal to , where is the number of positive integers less than or equal to that are relatively prime to .
2007, Jakub Pawlewicz, Order Statistics in the Farey Sequences in Sublinear Time, Lars Arge, Michael Hoffmann, Emo Welzl (editors), Algorithms - ESA 2007: 15th Annual European Symposium, Proceedings, Springer, Lecture Notes in Computer Science LNCS 4698, page 218,
The Farey sequence of order (denoted ) is the increasing sequence of all irreducible fractions from interval with denominators less than or equal to . The Farey sequences have numerous interesting properties and they are well known in the number theory and in the combinatorics.
en 2009 Michel Weber Dynamical Systems and Processes w:European Mathematical Society https://books.google.com.au/books?id=qFykm8apJuoC&pg=PA549&dq=%22Farey+sequence%22%7C%22Farey+sequences%22&hl=en&sa=X&ved=2ahUKEwiSrNC1vKLrAhUHX30KHT_1B00Q6AEwGHoECEMQAg#v=onepage&q=%22Farey%20sequence%22%7C%22Farey%20sequences%22&f=false 549 Riemann sums have also important connections with various problems from number theory, among them the Riemann Hypothesis, through their link with Farey sequences.
Usage notes
The sequence for given may be called the Farey sequence of order , and is often denoted .
The sequences are cumulative: each is contained in . The added elements are those fractions for which and are coprime.
The restriction that the fraction be in the range (i.e., numerator denominator) is sometimes omitted.
With the restriction in place, every Farey sequence begins with and ends with .
Related terms
en Farey neighbour
en Farey pair
en eponyms