Journal of Applied Mathematics

Volume 2014, Article ID 841826, 6 pages

http://dx.doi.org/10.1155/2014/841826

## The -Analogue of Riordan Representation of Pascal Matrices via Fibonomial Coefficients

^{1}Department of Mathematics, Faculty of Science, Gazi University, Teknikokullar, 06500 Ankara, Turkey^{2}Department of Mathematics, Faculty of Art and Science, Amasya University, Ipekkoy, 05100 Amasya, Turkey^{3}Faculty of Education, Konya Necmettin Erbakan University, Meram, 42099 Konya, Turkey^{4}Institute of Informatics, University of Gdańsk, Wita Stwosza 57, 80-952 Gdańsk, Poland

Received 8 February 2014; Revised 26 April 2014; Accepted 6 May 2014; Published 25 May 2014

Academic Editor: Fernando Simões

Copyright © 2014 Naim Tuglu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

#### Abstract

We study an analogue of Riordan representation of Pascal matrices via Fibonomial coefficients. In particular, we establish a relationship between the Riordan array and Fibonomial coefficients, and we show that such Pascal matrices can be represented by an -Riordan pair.

#### 1. Introduction

Pascal matrices are infinite matrices whose entries are formed by binomial coefficients. Fibonomial coefficients are a certain class of generalized binomial coefficients, and its theory is now well understood. The Fibonomial coefficients are used to define Pascal matrices, called Pascal matrices via Fibonomial coefficients.

The Riordan group is quite easily developed but unifies many themes in enumeration. In the recent literature, special attention has been given to the concept of Riordan arrays, which is a generalization of the well-known Pascal triangle. Riordan arrays are infinite lower-triangular matrices defined by the generating function of their columns. They form a group, called the Riordan group (see [1]). Some of the main results on the Riordan group and its application to combinatorial sums and identities can be found in Sprugnoli (see [2, 3]).

Setting infinite dimensional Pascal matrix via Fibonomial coefficients requires very long applications and operations, whereas it was seen that these long applications and operations can be culminated more short and in a practical way through the aid of Riordan representation. Therefore, one can obtain Pascal matrix via Fibonomial coefficients through the aid of Riordan representation.

The aim of this study is to establish the Riordan representation of Pascal matrices via Fibonomial coefficients. It is confronted by a problem while obtaining Riordan representation. Using the usual operation can not be a solution for this problem. For overcoming this problem, a new binary operation is required to define. By using this operation, -analogue of Riordan representation is obtained. In particular, we show that Pascal matrices via Fibonomial coefficients of the first and the second kinds can be represented with an -analogue of Riordan pair.

#### 2. Preliminaries

The Fibonacci sequence is the starting point of our discussion. Thus, we briefly review some basic concepts and properties of Fibonomial coefficients. The Fibonacci numbers are defined by the initial conditions , and the recurrence for . Let and be integers with . Then, the Fibonomial coefficients are defined by where and . It can be shown that Fibonomial coefficients satisfy the following recursion relation: (see [4–6]). Let . The Pascal matrix, , is defined by The Pascal matrix via Fibonomial coefficients is denoted by and is defined by where , and is the Fibonomial coefficient. Specially, is defined by Similarly, the generalized Pascal matrix via Fibonomial coefficients of the first kind, , is defined by and the generalized Pascal matrix via Fibonomial coefficients of the second kind, , is defined by Moreover, the extended generalized Pascal matrix via Fibonomial coefficients, , is defined by See [7–11] for details. Note that all of , , , and are matrices.

The Riordan group is a set of infinite lower-triangular matrices each of which is defined by two generating functions, called a Riordan pair. Any infinite matrix of this group is called a Riordan array, and Riordan arrays are generalizations of Pascal's triangle. In fact, Pascal matrices via Fibonomial coefficients are Riordan arrays, and we will show that they can be represented by a Riordan pair. To this purpose we briefly review the Riordan group and we refer to [1–3, 12, 13] for a detailed treatment of the subject.

*Definition 1 (see [1]). *Let and be two functions defined by
with . Let us denote by the infinite lower-triangular matrix whose th column is formed by the coefficients of the power series
The first column of this matrix is called the th column. Let be the set of all infinite lower-triangular matrices defined by (11), and let and . Then becomes a group under the operation
In particular, is called the Riordan group and any element of is called a Riordan pair. The identity element of is
And the inverse of any is
Here, is the compositional inverse of ; that is, .

#### 3. -Analogue of FTRA

In this section, firstly operation is defined and then using this operation a new theorem which is called -analogue of FTRA is obtained.

The generating functions of the Fibonomial coefficients [14–18] are where and . For simplicity of notation, we denote these two generating functions as follows.

*Definition 2. *Let ; then

*Definition 3. *Let denote the set of elements
for all integers and . Let be a binary operation defined as follows:

Lemma 4. *The pair is a monoid.*

*Proof. *(1) Closure. Indeed, for any two elements from we obtain an element from . That is,

(2) Associativity is satisfied straightforwardly.

(3) An identity element is

Let and belong to with and . The infinite lower-triangular matrix whose th column is formed by the coefficients of the power series is where . By using new binary operation and (21), we obtain a representation which is the analogue of the Riordan representation. We call the representation -analogue of Riordan representation and denote it by .

Therefore, we can write for any .

The following theorem is analogous to the fundamental theorem of Riordan arrays.

Theorem 5 (-analogue of FTRA). *Let with and . The -analogue of the fundamental theorem of Riordan arrays is
**
where the generating functions of the column vectors are given, respectively, by and . Then, equation of (23) is true if and only if the following equation holds:
*

*Proof. *Let with and . Then, it can be written as
where and . In this case, the matrix turns to
and thenand this yields
and we have our result.

#### 4. The -Analogue of Riordan Representation of Pascal Matrices via Fibonomial Coefficients

Obtaining the entries of infinite dimensional Pascal matrix via Fibonomial coefficients requires cumbersome calculations. However, there is an alternative method using the Riordan group which appears to be more convenient. To this purpose, we start with the following theorem in which we obtain the -analogue of Riordan representation of .

Theorem 6. *Let be the infinite Pascal matrix via Fibonomial coefficients as in (5). Then, the -analogue of Riordan representation of is given by
*

*Proof. *We consider the infinite Pascal matrix via Fibonomial coefficients . The entries of the th column are given by
Let
then
Using (22), we obtain
Taking (17) into account, we have
This proves that the generating function of the th column of is
In conclusion, the -analogue of Riordan representation of is

Corollary 7. *Let be in (6). Then, the -analogue of Riordan representation of is given by
*

Corollary 8. *Let be the Pascal matrix via Fibonomial coefficients of the first kind. Then, the -analogue of Riordan representation of is given by
*

Corollary 9. *Let be the Pascal matrix via Fibonomial coefficients of the second kind. Then, the -analogue of Riordan representation of is given by
*

Corollary 10. *Let be the extended generalized Pascal matrix via Fibonomial coefficients. Then, -analogue of the Riordan representation of is
*

#### Conflict of Interests

The authors declare that there is no conflict of interests regarding the publication of this paper.

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