Farey sequence

[′far·ē ‚sē·kwəns]

(mathematics)

The Farey sequence of order n is the increasing sequence, from 0 to 1, of fractions whose denominator is equal to or less that n, with each fraction expressed in lowest terms.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Farey Sequence

The Farey sequence of order n is the increasing sequence consisting of the fractions 0/1 and 1/1 and all the irreducible proper fractions whose numerator and denominator are greater than 0 and do not exceed n. For example, 0/1,1/3, 1/2, 2/3,1/1 is the Farey sequence of order 3.

If a/b and a’/b’ are two consecutive terms in a Farey sequence, then a’b – ab’ = 1. If a/b, a’/b’, and a”/b” are three consecutive terms in a Farey sequence, then a’/b’ = (a + a”)/(b + b”). The uses of Farey sequences include the approximation of irrational numbers by rational numbers and the reduction of binary quadratic forms.

The Farey sequence is named for the British scientist J. Farey, who reported some of its properties without proof in 1816.

Mentioned in

Diophantine Approximations

References in periodicals archive

It is interesting for us to watch these components budded along the boundary of the period-1 component in the manner of Farey sequence [17], according to the Schleicher's Algorithm [18].

The q-periodic components here are not likely to occur in the manner of Farey sequence. It is worthwhile to note that both Figures 7(d) and 8(c) contain Mandelbrot-like components.

Warwick, "The Farey Sequence," 2012, http://www.maths.ed.ac.uk/aar/fareyproject .pdf.

Dynamical Analysis via Mobius Conjugacy Map on a Uniparametric Family of Optimal Fourth-Order Multiple-Zero Solvers with Rational Weight Functions

The second describes the relation between edge conditions of the Farey graph F and the Farey sequences. Notice that the Farey sequence of order m [greater than or equal to] 1, denoted by [F.sub.m], is a sequence of reduced fractions x/y [member of] Q sorted in increasing order where [absolute value of (y)] [less than or equal to] m.

(3) The fractions are consecutive terms in the Farey sequence [F.sub.m] for some m.

Then a child in [Q.sub.n] and nonparents in [FT.sub.n] are certainly not consecutive terms in the Farey sequence [F.sub.m] for every m [member of] N.

Chromatic Numbers of Suborbital Graphs for the Modular Group and the Extended Modular Group

If one were to ask what area the Ford circles cover, one would need to think about whether every rational number is in a Farey sequence and how many fractions there are that have each possible denominator.

The relation mr - np = 1 calls to mind a property of Farey sequences, named after but not first discovered by a geologist, John Farey.

In this way, the same process that produces generations of circles makes Farey sequences.

Making connections

In algebra, a Farey sequence is the sequence of all fractions between 0 and 1 in which both the numerator and denominator are nonnegative and have no common divisors other than 1.

Dealing with non-English alphabets in mathematics

Each lesson centers on a key mathematical concept or application, with subjects including algebraic expressions and sequences, codes based on a simple fold, Benford's law, roots for divisibility tests and properties of numbers, the Farey sequences of order for fractions, interpretation of graphs, possibility tests and factors, estimation scales and units, symmetry, coordinates, averages and range, constructions, measurements, proofs, transformations, and sophisticated geometric forms.

50 mathematics lessons; rich and engaging ideas for secondary mathematics