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Perrin Chalkboard

 

Welcome to the Perrin Chalkboard!  I will be presenting in this blog a series of chalkboards which discuss interesting properties of the Perrin sequence and related integer sequences. This blog starts as a simple discussion of the Perrin sequence (the original mention by Lucas in 1876 and Perrin in 1899). It is found that an immense amount of research on the associated elliptic curves has occurred over the last 115 years. The Perrin sequence ties together much of the mathematics discussed today as algebraic number theory and modular functions. It is also integral to the discussion of Fermat’s Last Theorem conjectured in 1637 but proved by Wiles in 1994.

Theorems will be presented without proofs. I think the subject matter will appeal to those interested in the properties of integer sequences, elliptic equations, and graph theory. Many sequences from OEIS (On-line Encyclopedia of Integer Sequences) will be discussed, uncovering hidden or less obvious properties.

The primary subject matter in this blog covers the properties of integer sequences. However, it is not until Chapter 17 that I cover the subject matter of the short paper published by Perrin in 1899.  This chapter then introduces the subject of integer partitions, followed by some geometric applications of the Perrin sequence and then turns to division algorithms derived from general properties of cubic equations and associated integer sequences.

I encourage any comments or suggestions to the chalkboard subjects.

Although the pdf files are freely provided, if you are interested or have questions regarding any chapter please feel free to contact me.

Richard Turk
March 2015

Updated July 2017

Click on the pdf to open the first chapter.. or  continue scrolling to find the latest Chapter and pdf!

Board1_generation

 The Law of Cosines and Generation of Sequences from Phasors

The addition of phasors as mentioned in the last chapter can be simplified using the law of cosines.  When two vectors in the complex plane are added the resulting vector magnitude and argument are altered.  The summation in a complex ellipse of two conjugate vectors results in a vector along the real axis.  The law of cosines is an extension of the Pythagorean theorem for triangles not containing an angle of 90 degrees.  All phasors of complex conjugate solutions can be added based on this law.  For integer sequences, the powers of these solutions are vectors which align at 0 or 180 degrees on the complex plane. 

Board 54- Law of Cosines, Generation of Sequences from Phasors

Chapter 53 The Perrin Sequence, Octagons, Ellipses and Phasors

The complex octagon is calculated for complex solutions of polynomials. Using the Perrin polynomial that generates the sequence it is shown that the complex solution can be expressed as a phase vector or phasor. Phasors are used by electrical engineers and physicists in describing current and power in electrical circuits. In a similar manner, the complex phasor describes an ellipse in which the phase represents complex numbers that are roots of other polynomials. These polynomials all factor into the discriminant (-23) of the Perrin polynomial. The phasors can be added and multiplied like electrical components to design other polynomials containing information similar to Perrin’s polynomial. The periodicity of the phase vector for each root of a polynomial suggests that a Fourier Transform on the phasors can provide information about the integer sequence.

Updated Post

Board53_The Perrin Sequence, Octagons, Ellipses and Phasors

Chapter 52 Complex Octagonal Geometry of Sequences

A complex octagon is represented as a group of all polynomials with negative discriminants and at least one real root.  Elliptic functions and hypergeometric functions are used to transform polynomials with positive discriminants into the complex octagon. The properties of the complex octagon for several discriminants are presented and indicate it is a precise and well-defined representation of real roots of any polynomial. Simplified methods of finding these roots using modular functions are described.

The Octagonal Geometry of Sequences

Chapter 51 New Sequences from the Weber g Class Invariants

Integer sequences are part of our mathematical and physical environment.  This book has described many different classes of sequences which have been shown to be derived from various mathematical principles.  In this chapter I return to the q-octic fraction that transforms a negative integer into a real solution of the Weber functions.  The q-octic fraction is not limited to Weber functions and it is shown that real numbers between integers can be transformed into real solutions of potentially an infinite number of polynomial sequences. Expressions are derived that can generate sequences only from the norm of the q-octic fraction suggesting the Ramanujan ladder is a continuous function of negative real numbers and calculate real solutions to polynomials of integer degree.    

Board51_New Sequences from the Weber g Class Invariant

Chapter 50  Integer Sequences and Orthogonal Polynomials

Our previous chapters have demonstrated that various functions can be used to express integer sequences or linear recurrences.  The intersystem polynomials (ISP) were shown to be equivalent to Bell Polynomials for sequence numbers of polynomials of any degree.  Binomial coefficients and the incomplete Beta function could be developed to calculate Perrin numbers. These equations lead to expressions of sequence numbers using the hypergeometric functions and  the specialized form of the Jacobi Polynomial.  Polynomials obtained from the cycle index of symmetric groups were also shown to be equivalent to these orthogonal polynomials.  In this Chapter the parent sequence and its first convolution, the element sequence of even power polynomials are two sequences that are also expressed by the Jacobi and hypergeometric functions.

Board50_Integer Sequences and Orthogonal Polynomials

Chapter 49- Q Transforms and the g Class Invariants

 

Some further relationships between modular functions and the moduli of q- octic continued fractions (QCF) are developed.  The transforms are modular- like but remove the need for complex multiplication.  They can be applied to the calculation of the g class invariants for both odd and even integer discriminants. Some integer sequences are discussed which are associated with the transform L2.

Board49 Q Transforms and g Class Invariants

Chapter 48 – Solving the Quintic Using Methods Available in the 19th Century

In 1858 Charles Hermite and simultaneously Leopold Kronecker published “On the Solution of the General Equation of the Fifth Degree”.  Using the elliptic function and methods available to the mid- 19th century mathematician, the approach to solving fifth degree polynomials was finally solved after centuries of unsuccessful attempts.  Having discussed symmetry of odd order equations to solve sequence number in the last Chapter, I find a similar symmetry required to solution of the quintic.  A three-step process reflecting a workable methodology of the 1800s is demonstrated with a particular general example.

Solving the Quintic using Methods Available in the 19th Century

Chapter 47- Cycle Index of the Symmetric Group and the Jacobi Polynomial

Under certain conditions the cycle index of symmetric group sums are shown to be equivalent to limiting Jacobi Polynomials or hypergeometric equations of special form when z=1. These sums are found to be numbers from select element sequences such as the Padovan sequence.  Expanding the space of symmetric groups by changes in two parameters g and j, allows for similar calculation of numbers from other classes of sequences.  The common theme of these sequences is the coloration of objects within various symmetric groups. Sequence numbers are shown to be expansions of the cycle indices in powers of the constant coefficient of a class of polynomials of odd order. Special non-linear recurrences occur when g is or j is an even integer. 

Cycle Index of Symmetry Groups and the jacobi Polynomial

 

Chapter 46-Equations for Ramanujan Class Invariants and the Ramanujan Ladder

Ramanujan__Ladder (2)

Attached are useful formula for those interested in calculating Ramanujan class invariants and examining the relationships to the properties of the associated octahedron, the Ramanujan octaves and the Ramanujan ladder. Many of the formula are discussed in Chapters 28 to 32 in the Perrin Chalkboard.

Ramanujan_Class_Invariants_and the_Ramanujan_Ladder

Chapter 45- Elliptic Functions, Bell Polynomial and Applications

The previous three chapters discuss the partial Bell Polynomial and its application to integer sequences and various polynomials.  A new formula using the Bell Polynomial to calculate Jacobi elliptic functions is described in this paper.  The infinite polynomial expansion calculates the inverse of the elliptic integrals of the first and second kind.  A single formula for the elliptic sine function, sn, is sufficient to calculate all 12 elliptic functions associated with the elliptic integral of the first kind.  A corresponding formula for the elliptic integral of the second kind is also described.

These functions are used in various applications such as the geometry of ellipses and in astrophysics such as calculation of relativistic elliptical orbits of planets and comets.  Examples of calculated elliptical and hyperbolic orbits such as the precession of the perihelion of the planet Mercury are shown using the Bell Polynomial (sn) function. An association of the Bell Polynomial function to the q octic and the Ramanujan ladder for Weber’s class invariants is discussed

Bell and Elliptic functions