2. Generalized John Polynomials
In this section, we provide a comprehensive analysis of the generalized Leonardo type Pell polynomials which is called generalized John polynomials in the rest of the study, exploring its fundamental algebraic and structural characteristics. We begin by establishing its Binet-type formula and the corresponding generating function, which serve as the primary tools for our subsequent derivations. Our investigation then extends to several classical identities well-documented in the literature, including those of Catalan, Cassini, Vajda, and d’Ocagne, demonstrating how these properties are integrated into this broader non-homogeneous framework. Furthermore, we present an explicit representation of these polynomials, typically expressed through nested summations or related sequences. In addition to these identities, we establish various theorems regarding matrix representations and determinantal values, which highlight unique properties that remain independent of the variable x. To initiate our formal treatment, we define the generalized John polynomials through a second-order linear non-homogeneous recurrence relation as follows.
Definition 1.
Let n be an integer with , then the generalized John polynomials is defined, with second order linear non homogeneous recurrence relation:
with the initial condition and where is an arbitrary polynomial in x.
If we take we obtain generalized Pell polynomial but in this study we assume that unless otherwise stated.
Next, we define four distinct cases of generalized
John polynomials, which satisfy a second-order linear non-homogeneous recurrence relation genereted by (
27), as follows.
Definition 2. For ,
-
(a)
-
Generalized John polynomial is defined as
with the initial condition and where is a polynomial in
-
(b)
-
Generalized John polynomial is defined as
with the initial condition and where is a polynomial in
-
(c)
-
Generalized John polynomial is defined as
with the initial condition and where is a polynomial in
-
(d)
-
Generalized John polynomial is defined as
with the initial condition and where is a polynomial in
It is clear that, for taking each polynomial
in the recurrence relations (
28)-(
31) generate distinct
Leonardo-Pell polynomials.
Theorem 1.
For , we give closed form solution of generalized John polynomials as follows:
where the particular solution is
and homogeneous solution is
with the arbitrary initial condition
Proof. The generalized
John polynomials defined by (
27) can be given with homogeneous solution denoted as
and a particular solution denoted as
So
can be given as
The homogeneous part has the second order recurrence relation given as follow:
with the initial condition
and
Since the non-homogeneous term of (
27) is independent of the index
the particular solution
is the form of a polynomial
Substituting this constant particular solution into the recurrence relation (
32) , we obtain
-
(
33) leads to the characteristic equation
where the roots are
and
where
Using [[
15], Theorem 1] we obtain
with the initial condition
and
This completes the proof. □
Having established the closed-form solution of in Theorem 1, we now refine this result into a more explicit representation, as formulated in the following lemma.
Lemma 1.
The identity (32) can be written as follows.
Proof. Using the Binet’s formula of Pell polynomial, [
16], identity (1.7)],
the proof follows easily. □
Using Theorem 1, we present four distinct cases of generalized John polynomials recursively as follows.
Corollary 1. For we have
-
(a)
with the initial condition and
-
(b)
with the initial condition and
-
(c)
with the initial condition and
-
(d)
with the initial condition and
Now, we define five special types of
John polynomial with assuming special cases of
. Here
,
,
, and
are defined by A.F Horadam in [
14] but in this study we define John-Lucas polynomial denoted as
Notation: We denote as , , , respectively.
Definition 3. For we have
-
(a)
-
By taking in Definition 2, (a) MinMax polynomial can be defined as ,
with the initial condition and Note that: MinMax polynomial can be called as John polynomial.
-
(b)
-
By taking in Definition 2, (b) Subsidiary MinMax polynomial can be defined as, ,
with the initial condition and
-
(c)
-
By taking in Definition 2, (a) MinMax polynomial can be defined as,
with the initial condition and
-
(d)
-
By taking in Definition 2, (c) Subsidiary MinMax polynomial can be defined as,
with the initial condition and
-
(e)
-
By taking in Corollary 2, (d) John-Lucas polynomial can be defined as, ,
with the initial condition and
The sequence of John polynomials satisfies the third order homogeneous recurrence relation given in the following lemma.
Lemma 2.
For John polynomial can be written as third order recurrence relation:
with the initial condition , and
Proof. Using (
27), the identity is proved easily. □
Note that in Lemma 2, the third initial condition is strictly determined by , , and the polynomial . By relaxing this structural dependency and treating the third initial term as an arbitrary polynomial, we can capture a much broader family of sequences. This motivates the introduction of the generalized sequence , defined as follows.
Definition 4.
For the generalized John polynomial is defined as, recursively,
with the arbitrary initial condition , and
It is worth noting that the recurrence (
35) can be extended to negative subscripts, i.e,
However, in such a case,
may not represent a polynomial in the usual sense. Hence, the recurrence (
35) holds for all integer
This recurrence relation (
35) gives following characteristic equation.
where roots of this equation are
and
such that
Hence, polynomial sequences , , , and satisfy third order homogeneous recurrence relation given below.
Corollary 2. For we have
-
(a)
with the initial condition and
-
(b)
with the initial condition and
-
(c)
with the initial condition and
-
(d)
with the initial condition and
-
(e)
with the initial condition and
Here, we present the first few values of polynomial sequences , , , and as follow, respectively.
,
, , , ,
, , ,
, , , , ,
, , , ,
In the subsequent theorem, we establish the Binet-type representation for the generalized John polynomials, thereby providing a closed-form expression that encapsulates their structural properties.
Theorem 2.
For all integer the Binet’s formula of generalized John polynomial can be given as follow.
where
Proof. Set
in [[
17], Theorem 1].
By applying the preceding theorem, or alternatively Theorem 1, we are able to derive the following set of results, which further clarify the structural properties of the generalized John polynomials.
Corollary 3. For all integer we have following formulas.
-
(a)
-
(b)
-
(c)
-
(d)
-
(e)
In the next theorem we present generating function of generalized John polynomials.
Theorem 3.
Suppose that is the ordinary generating function of the generalized John (sequence of) polynomials. Then is given by
Proof. Set
in [
17], Lemma 9]. □
Theorem 3 gives in the following corollary.
Corollary 4. For generalized John polynomials, we have,
-
(a)
-
(b)
-
(c)
-
(d)
-
(e)
In the forthcoming theorem, we derive the exponential generating function associated with the generalized John polynomials, thereby providing a powerful analytic tool for studying their structural and combinatorial properties.
Theorem 4.
Suppose that is the exponential generating function of the generalized Leonardo-Pell (sequence of) polynomials. Then is given by
where and as stated in the Theorem 2.
Proof. For the proof, we derive following equalities.
Then we obtain
The solution of this diferantial equation is
For
we obtain
This implies
,
,
This completes the proof. □
In the following lemma, we present the third-order homogeneous representation of second-order linear non-homogeneous Horadam-Leonardo polynomial sequences, that is necessary to construct the general determinantal representations presented later in this paper.
Definition 5.
For all integers n, we define generalized Horadam Leonardo polynomials with non-homogeneous second order recurrence relation as follows:
with arbitrary initial condition , and , s are polynomials in x.
Based on the considerations above, while the term in the standard Horadam Leonardo polynomials depends on the first two terms, we now introduce a more generalized framework by assuming as an additional arbitrary initial condition. We believe that this selection enriches the scope of our study by providing a more comprehensive and versatile mathematical structure. Hence, next definition we present generalized Horodam-Leonardo polynomials.
Definition 6.
The generalized Horadam-Leonardo polynomials for are given by the following homogeneous recurrence relation:
with arbitrary initial condition and
Note:
satisfying (
37) can be written in the form (
38).
A combinatorial formula is often the most direct tool for exploring the exact structure of a sequence. With this in mind, the next theorem establishes an explicit representation for the generalized Horadam-Leonardo polynomials.
Theorem 5.
For we have the following formula.
Proof. For the proof, we use some basic properties of power series and combinatorial formulation. First we can write
and
If we take
we obtain
since
So we have
For the next step of the proof we denote
Then assuming
we can write
This gives us
Then, we decompose the generating function of the generalized Horadam-Leonardo polynomials given in [[
17], Lemma 9] into partial fractions, we obtain
where
as stated in the theorem. So we obtain,
Therefore, we get
This completes the proof. □
In the subsequent theorem, we present combinatorial presentation of generalized John polynomials.
Theorem 6.
For we have the following formulas.
where
Proof. For the proof, set in Theorem 5. □
As a consequence of the previous theorem, we obtain the following result.
Corollary 5. For we have the following formula.
Hence, the following theorem provides a determinantal presentation for the generalized Horodam-Leonardo polynomials.
Theorem 7.
For and we have following formula.
where
Note that, we read all the nonmentioned entries as zero.
Proof. For the proof we use LU decomposition using Doolittle algorithm. Before proceeding the proof, we recall
decomposition using Doolittle algorithm [
19]. We assume that the lower and upper triangular matrices
L and
U of size
respectively, is given as follow
and
, if
The matrix
of size
n can be factor as follow
where using Dooolittle algorithm, we obtain the following equalities:
Therefore, we deduce the following equalities:
This implies
Since
and
we obtain
By applying this general determinantal result to our specific sequence, we immediately obtain the following theorem.
Theorem 8.
For and we have the following formula.
where
Note that, we read all the nonmentioned entries as zero.
Proof. For the proof, replace in Theorem 7. □
The following corollary gives special cases of Theorem 8.
Corollary 6. For we have the following formulas:
-
(a)
-
(b)
-
(c)
-
(d)
-
(e)
We proceed by formulating Catalan’s identity for the generalized John polynomials.
Theorem 9 (Catalan’s identity)
. For all integer we have
Proof. Using Binet’s formula of generalized John polynomials, we have,
If we take in the above theorem we have the following corollary.
Our next objective is to state d’Ocagne’s identity for the generalized John polynomials.
Theorem 10 (d’Ocagne’s identity)
. For all integer then we have,
Proof. Using Binet’s formula of generalized John polynomials, we have,
We now aim to determine Vajda’s identity for the generalized John polynomials.
Theorem 11 (Vajda’s identity)
. For all integer we have,
Proof. Using Binet’s formula of generalized John polynomials, we have, the required identity.
Let us now explore Honsberger’s identity in the context of the generalized John polynomials.
Theorem 12 (Honsberger’s identity)
. For all integer we have the following formulas.
Proof. For the proof set
in [[
17], Theorem 53]. □
Also, the last theorem gives following corollary.
Corollary 8.
For all integer n, we have
In the following theorem, we determine an identity that describes the relationship between generalized John polynomials and polynomial .
Remark 1.
[[4], page 320 identity (7.21)]Let be the generating function of sequence of then we have
Theorem 13.
For we have the following formula.
Proof. Using Corollary
5, and Remark 1, we get
Using (
40) and (
36) we obtain,
Hence we have
Thus, the proof is completed. □
The last theorem gives us following Theorem.
Proof. Using [[
15], Theorem15] and and using identity (
15), we have
Then, Theorem 14 gives the following theorem which provides an alternative proof of Theorem 5.
Proof. Using Theorem 14 and identity (
21), the proof can be done. □
Now, using Theorem 15 and Theorem 14, we derive the following corollary.
Corollary 9. For we have the following equalities.
Next, we give several identities that are relevant to matrix theory. To become more specific, we use the generalized John polynomials to construct a family of square matrices of order three. These matrices are built such that their entries can be expressed in relation to the polynomial sequence, permitting the exploration of structural properties, recurrence relations, and determinant formulas that result from the interplay between polynomial theory and linear algebra.
As a result, we may apply the matrix representations given above to find an important structural relationship for the generalized John polynomials. We can now use this framework to establish the following theorems.
Theorem 16.
For all integer we have
Proof. The proof can be done by using strong induction on
First, if we take
the statement of the theorem is hold. Next assuming the statement of the theorem is true for
then for
, we obtain
The other case can be proof similarly. □
If we take determinant of the statement given in the Theorem 16, we obtain the following corollary.
Corollary 10 (Simpson’s formula)
. For all integer we have
Using and we can state the following theorem.
Theorem 17. The following properties hold: for all integers ,
-
(a)
.
-
(b)
-
(c)
Proof. Set
in [
17], Theorem 51]. □
In the next lemma we give formula related to derivative of the power of the square matrix.
Lemma 3.
Let be a square matrix function in variable and then we have
Proof. For the proof, see [[
21], p. 207]. □
In the next theorem, we state the derivative of the generalized John polynomials.
Theorem 18.
For we have the following equality.
Proof. First, we define the vector
then we obtain
This identity can be proof using induction on
Then, if we derive both side of the equation (
41) and using Lemma 3 and Theorem 17, we obtain
In the next corollary, some derivative formulas are given for the special cases of John polynomials.
Corollary 11. For we have the following equalities.
-
(a)
-
(b)
-
(c)
-
(d)
-
(e)