Global Journal of Mathematical Analysis, 2 (4) (2014) 249-258
©Science Publishing Corporation
www.sciencepubco.com/index.php/GJMA
doi: 10.14419/gjma.v2i4.3126
Research Paper
Generalized Fibonacci-Like Polynomials and Some Identities
Mamta Singh 1, Yogesh Kumar Gupta 2, Omprakash Sikhwal3*
1
Department of Mathematical Sciences and Computer Application, Bundelkhand University, Jhansi (U. P.) India
2
School of Studies in Mathematics, Vikram University Ujjain, India
3
Department of Mathematics, Mandsaur Institute of Technology Mandsaur (M. P.) India
*Corresponding author E-mail:
[email protected]
Copyright © 2014 Mamta singh 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
The Fibonacci polynomials and Lucas polynomials are famous for possessing wonderful and amazing properties and
identities. In this paper, Generalized Fibonacci-Like Polynomials are introduced and defined by
mn ( x) xmn1 ( x) mn2 ( x), n 2. with m0 ( x) 2s and m1 ( x) 1 s , where s is integer. Further, some basic identities are
generated and derived by standard methods.
Keywords: Fibonacci Polynomials, Lucas Polynomials, Generalized Fibonacci-Like Polynomials, Binet’s formula.
1. Introduction
The Fibonacci polynomials and Lucas polynomials are famous for possessing wonderful and amazing properties and
identities. It is well-known that the Fibonacci polynomials and Lucas polynomials are closely related and widely
investigated. Fibonacci polynomials appear in different frameworks. These polynomials are of great importance in the
study of many subjects such as algebra, geometry, combinatorics, approximation theory, statistics and number theory
itself. Moreover these polynomials have been applied in every branch of mathematics. Fibonacci polynomials are
special cases of Chebyshev polynomials and have been studied on a more advanced level by many mathematicians.
Basin, S. L. [1] show that Q matrix generates a set of Fibonacci Polynomials is defined by the recurrence formula
(1.1)
f n 1 ( x) xf n ( x) f n 1 ( x), n 2 with f 0 ( x) 0, f 1 ( x) 1.
The Lucas Polynomials is defined by the recurrence formula
ln 1 ( x) xln ( x) ln 1 ( x), n 2 with l0 ( x) 2, l1 ( x) x.
(1.2)
Generating function of Fibonacci polynomial is
f xt
n 0
t 1 xt t 2
n
n
1
(1.3)
Generating function of Lucas polynomial is
l x t
n0
n
n
2 xt 1 xt t 2
1
(1.4)
Explicit sum formula for (1.1) is given by
f n ( x)
n 1
2
n k 1 n 1 2 k
.
x
k
k 0
n
where a binomial coefficient and [x] is define as the greatest integer less than or equal to x.
k
Explicit sum formula for (1.3) is given by
(1.5)
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Global Journal of Mathematical Analysis
n
2
n n k n2k
x .
k 0 n k k
ln ( x)
(1.6)
n
where a binomial coefficient and [x] is defined as the greatest integer less than or equal to x.
k
Fibonacci-Like polynomials [11] is defined by the recurrence relation:
sn x xsn-1 x sn 2 x , n 2 with initial terms s0 x = 2 and s1 x =2x.
(1.7)
Generalized Fibonacci-Lucas Polynomials [12] is defined by recurrence relation.
bn x xbn-1 x b n-2 , x , n 2 With initial conditions b0 x 2b and b1 x s ,
(1.8)
where b and s are integers.
The Fibonacci and Lucas polynomials possess many fascinating properties which have been studied in [2] to [12].
In this paper, Fibonacci-Like Polynomials are introducing with some basic identities and derived by standard method.
2. Generalized Fibonacci-Like Polynomials:
Generalized Fibonacci-Like Polynomials mn x are defined by recurrence relation
mn ( x) xmn1 ( x) mn2 ( x), n 2. with m0 ( x) 2s and m1 ( x) 1 s , where s is integer.
(2.1)
The first few terms of generalized Fibonacci-Like Polynomials are as follows:
m0 ( x) 2s ,
m1 ( x) 1 s ,
m2 ( x) (1 s) x 2s ,
m3 ( x) (1 s) x 2 2sx (1 s) and so on.
If x=1, then mn (1) is generalized Fibonacci-Like sequence.
The characteristic equation of recurrence relation (2.1) is
x
x2 4
2
and
x
2 x 1 0
x2 4
2
(2.2)
Also, 1 , Binet’s formula of Generalized Fibonacci-Like sequence is defined by
mn x An Bn
x
mn x A
n
x2 4
B x
2
x2 4
2
n
Here, A 2s x and B 2s x .
Also, AB
4s 2
(2.3)
2
, A B m0 ( x) 2s,
x 2 4,
and 2 2 x 2 5.
Generating function of Generalized Fibonacci-Like Polynomials is
2s 1 xt 1 s t
mn x t n
.
n 0
1 xt t 2
Now Hyper geometric representation of generating function
m xt
n 0
n
n
2s 1 xt 1 s t 1 xt t 2 ,
1
1
2s 1 xt 1 s t 1 x t t ,
(2.4)
(2.5)
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m xt
n 0
n
n
2s 1 xt 1 s t x t t n
n
n0
n
n
2s 1 xt 1 s t .t n x n k .t k
n 0
k 0 k
n
n!
2s 1 xt 1 s t .
x n k .t k n
n 0 k 0 k ! n k !
2s 1 xt 1 s t .
n k !
k!n !
n 0 k 0
xt n
n 0
n!
2s1 xt 1 s t .
2s 1 xt 1 s t e xt
n k
k 0
2s 1 xt 1 s t e xt
k 0
2s 1 xt 1 s t e
n!
x n .t 2 k n
n k ! .t 2 k
n! k!
k 0
t
2 k
.
k!
n k 1 t
.
k!
nk
2
k
1k t 2
1
.
n
k
1k k !
k 0
xt
k
2s 1 xt 1 s t e xt 2 F1 n 1:1;1; t 2 ,
m x t
n
n
n 0
2s 1 xt 1 s t e xt 2 F1 n 1:1;1; t 2
(2.6)
3. Some Identities of Generalized Fibonacci-Like Polynomials
In this section, we present some identities like Catalan’s; Cassini’s; d’Ocagne’s identities etc. by Binet’s formula or
explicit sum formula or generating function.
Theorem 3.1: Prove that
mn 1 x mn 1 x xmn x , n 1.
(3.1)
Proof: By Generating function of Fibonacci-Like polynomials, we have
m xt
n 0
2s 1 xt 1 s t 1 xt t 2
n
n
1
Differentiating both sides with respect to t, we get
2
1
n1 2s 1 xt 1 s t x 2t 1 xt t 2
1 s 2sx 1 xt t 2
nmn x t
n 0
1 xt t nm x t
2
n 0
1 xt t nm x t
2
n 0
nm x t
n0
n
n 1
n 1
n
n
n 1
2s 1 xt 1 s t x 2t 1 xt t 2 1 s 2sx
1
x 2t mn x t n 1 s 2sx
n 0
n0
n0
n0
n0
xnmn t n nmn x t n 1 xmn x t n 2mn t n 1 1 s 2sx
Now equating the coefficient of t n on both sides we get,
n 1 mn1 x nxmn x n 1 mn1 x xmn x 2mn1 x ,
n 1 mn1 x n 1 mn1 x n 1 xmn x ,
mn 1 x mn 1 x xmn x
This is required results.
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Global Journal of Mathematical Analysis
Theorem 3.2: Prove that
mn' x xmn' 1 x mn 1 x mn' 2 x , n 2.
(3.2)
Proof: By generating function of Fibonacci-Like polynomials, we have
m xt
n 0
2s 1 xt 1 s t 1 xt t 2
n
n
1
Differentiating both sides with respect to x, we get
m xt
n 0
n
2s 1 xt 1 s t 1 xt t 2 ,
n
2s 1 xt 1 s t 1 1 xt t 2
1
n
m xt
n0
'
n
1 xt t m x t
2
'
n
n 0
2
'
n
n 0
2s 1 xt 1 s t 1 1 xt t 2
n
t mn x t n 2st ,
n 0
n
n 0
'
n
1
1
t 2st
m x t xm x t
'
n
t 1 xt t 2 2st
n
1 xt t m x t
2
n 0
n 1
n 0
n 0
mn' x t n 2 t mn x t n 1 2st ,
Now equating the coefficient of t n , we get
mn' x xmn' 1 x mn' 2 x mn 1 x .
mn' x xmn' 1 x mn 1 x mn' 2 x .
Theorem 3.3: Prove that
mn' 1 x xmn' x mn x mn' 1 x , n 1.
(3.3)
Proof: By (3.1), we have
mn 1 x mn 1 x xmn x , n 1.
By differentiating with respect to x, we get
mn' 1 x mn' 1 x xmn' x mn x ,
mn' 1 x xmn' x mn x mn' 1 x .
Theorem 3.4: Prove that
nmn x xmn' x 2mn' 1 x . , n 1 and xmn' 1 x n 1 mn 1 x 2mn' x , n 1.
Proof: By generating function of Fibonacci-Like polynomials, we have
m xt
n 0
n
n
2s 1 xt 1 s t 1 xt t 2 .
1
Differentiating both sides with respect to t, we get
nm x t
n 1
n
n0
1 s 2sx 1 xt t 2 2s 1 xt 1 s t x 2t 1 xt t 2
1
2
.
(3.4)
Differentiating both sides with respect to x, we get
m xt
n0
'
n
n
2st 1 xt t 2 2s 1 xt 1 s t .t 1 xt t 2
1
'
n
n 1
2s 1 xt t 2 2s 1 xt 1 s t 1 xt t 2
m xt
n 1
2s 1 xt t 2 2s 1 xt 1 s t 1 xt t 2
m xt
n0
n 0
'
n
1
1
2
2
2
(3.5)
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Global Journal of Mathematical Analysis
Using (3.5) in (3.4), we get
'
2 1
2 1
n 1
n 1
nm
x
t
1
s
2
sx
1
xt
t
x
2
t
mn x t 2s 1 xt t ,
n
n0
n0
nm x t
n0
nm x t
n0
n
n 1
1 s 2sx 1 xt t 2 x 2t mn' x t n 1 2s x 2t 1 xt t 2
n 1
1 s 2sx 1 xt t
n
1
1
n0
2 1
n0
n0
x mn' x t n 1 2mn' x t n 2s x 2t 1 xt t 2
1
Equating the coefficient of t n 1 on both sides, we get
nm n x xm n' x 2m n' 1 x .
(3.6)
n
Again equating the coefficient of t , we get
n 1 mn1 x xm'n1 x 2m'n x ,
xmn' 1 x n 1 mn 1 x 2mn' x . .
(3.7)
Theorem 3.5: Prove that
n 1 mn x m'n1 x m'n1 x . , n 1 .
Proof: By (3.1), we have
mn 1 x mn 1 x xmn x , n 1.
By differentiating with respect to x, we get
m'n 1 x m'n 1 x xm'n x mn x ,
xm'n x mn x m'n 1 x m'n 1 x .
(3.8)
Using equation (3.5) in equation (3.8) we get
nmn x 2m'n 1 x mn x m'n 1 x m'n 1 x ,
nmn x mn x m'n 1 x 2m'n 1 x m'n 1 x ,
n 1 mn x m'n1 x m'n1 x .
(3.9)
Theorem 3.6: Prove that
xmn' x 2mn' 1 x n 2 mn x , n 0.
Proof: Using equation (3.7) in equation (3.9), we get
1
n 1 mn x mn' 1 x nmn x xmn' x ,
2
2 n 1 mn x 2mn' 1 x nmn x xmn' x ,
xmn' x 2mn' 1 x nmn x 2n 2 mn x ,
xmn' x 2mn' 1 x n 2n 2 mn x ,
xmn' x 2mn' 1 x n 2 mn x .
(3.10)
Theorem 3.7: n 1 xm'n x nm'n 1 x n 2 m'n 1 x , n 1.
Proof: Using equation (2.3) we get
n 1{m'n1 x xm'n x m'n1 x } m'n1 x m'n1 x
n 1 m'n1 x n 1 xm'n x n 1 m'n1 x m'n1 x m'n1 x ,
n 1 m'n1 x n 1 m'n1 x m'n1 x m'n1 x n 1 xm'n x ,
nm'n 1 x n 2 m'n 1 x n 1 xm'n x .
n 1 xm'n x nm'n1 x n 2 m'n1 x .
(3.11)
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Global Journal of Mathematical Analysis
Theorem 3.8 (Explicit sum formula): For Generalized Fibonacci-Like polynomials are given by
n
2
n k n2k
.
mn x 2s
x
k 0 k
(3.12)
Proof: By generating function (2.5), we have
m xt
n 0
2s 1 xt 1 s t 1 xt t 2
n
n
1
2s 1 xt 1 s t 1 xt t 2
1
2s 1 xt 1 s t x t t n
n
n 0
n
n
2s 1 xt 1 s t .t n x n k .t k
n 0
m0 k
n
n!
2s 1 xt 1 s t .
x n k .t k n
n 0 m 0 k! n k !
n
2s 1 xt 1 s t .
n 0 m0
2s 1 xt 1 s t .
n 0 m0
n
2
mn x 2s
n k !
k 0 k ! n 2k !
n k !
k!n !
n k !
k!n !
x n .t 2 k n
x n .t 2 k n ,
xn2k .
Equating coefficients of t n on both sides, we get required explicit formula.
Theorem 3.9 For positive integer n 0 , prove that
4
n n 1
mn x 2sx n 2 F1
:
; n; 2 .
2
x
2
.
Proof: By explicit sum formula (3.13), it follows that
(3.13)
n
2
n k n2k
,
mn x 2s
x
k 0 k
mn x 2sx
mn x 2sx
n
2
n
1 1n n 2k
2k
k 0 n 1
1n
k
k
n
2
mn x 2sx n
1
k 0
mn x 2sx
2 k
n
2
n
,
k 0
n
2
n
n k !
k ! n 2k ! x
k 0
1
k
k
x 2 k
,
k!
2 k
n n 1 x
22 k
2 k 2 k k!
,
2k
n k 1
n n 1 4
22 k
2
2 k 2 k x
.
n k k !
Hence,
4
n n 1
mn x 2sx n 2 F1 ,
; n, 2 .
2
2
x
Theorem 3.10: For positive integer n 0 , prove that
c c 1
tn
n 1 n 2
t2
c
, n 1,
,
,
c n mn x 2s 1 xt 3 F1 ,
n!
2
2 1 xt 2
n0
2 2
.
(3.14)
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Global Journal of Mathematical Analysis
Proof: Multiplying both sides of (3.13) by c n
c n mn x t
n 0
n
2
n k!
tn
c n x n 2 k ,
n
n 0 k 0 k ! n 2k !
n k!
2s
c n 2 k x n t n 2 k
k
!
n
!
n
2
k
!
n 0 k 0
n k!
n
2s
c 2k n c 2k xt t 2k
n 0 k 0 k !n ! n 2k !
n
tn
and summing between the limit n=0 to n , we obtain
n!
2s
n
xt n k !
2 s c 2k n
c 2 k t 2 k
!
!
2
!
n
k
n
k
n0
n 0
n k!
c 2 k
2s 1 xt
c 2 k t 2 k
k 0 k ! n 2k !
n k!
c 2 k
2s 1 xt
c t 2k
k !n 2k ! 2 k
k 0
2s 1 xt
n k!
c 2 k
k 0 k ! n 2k !
c
2s1 xt
c
2s 1 xt
c
2s 1 xt
c
2s1 xt
c
t
n
k
2
n k!
22 k c c 1 t 2
2 k 2 k 1 xt
k 0 k ! n 2 k!
n k!
k
2
n!
22 k c c 1 t 2
2 k 2 k 1 xt
k 0 k!n 2k!
n 1k
c
c 1
t2
2k
2
2
2 k 2 k 1 xt
k 0 n 1 2 k
n 1k
c
k
k 0
2 s 1 xt
t2
1 xt
n 1 n 2
2 2k
2 k 2 k
2
2k
k
2
c c 1 t
2
2 k 2 k 1 xt
k
c c 1
k
n 1 k
t2
2 k 2 k
.
2
n 1 n 2
s 0
1 xt
2 k 2 k
Hence, c n mn x 2s 1 xt
n!
n 0
c
n 1 n 2
c c 1
3 F1 2 , 2 , n 1, 2 , 2 ,
.
2
xt
1
t2
Theorem 3.11 (Explicit sum formula): For Generalized Fibonacci-Like polynomials
n
2
n k n2k
mn 1 x 1 s 2sx
x .
k 0 k
(3.15)
Proof: Generating function (2.5), we have
m xt
n 0
n
n
2s 1 xt 1 s t 1 xt t 2 ,
1
2s 1 xt 1 s t 1 xt t 2
1
2s 1 xt 1 s t x t t n ,
n 0
n
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Global Journal of Mathematical Analysis
n
n
2s 1 xt 1 s t .t n x n k t k ,
n 0
m 0 k
n
n!
2s 1 xt 1 s t .
x n k .t k n
n 0 m 0 k! n k !
m xt
n 0
n
n
n
2s 1 xt 1 s t .
n k !
k!n !
n 0 m0
2s 1 xt 1 s t .
n k !
k!n !
n 0 m0
x n .t 2 k n
x n .t 2 k n .
Equating coefficients of t n on both sides, we get required explicit formula
n
2
mn x 2s
n k !
k 0 k ! n 2k !
xn2k .
Equating coefficients of t n 1 on both sides, we get required explicit formula
n
2
n k !
mn 1 x 1 s 2s
xn2k .
k 0 k ! n 2k !
Theorem 3.12 (Catalan’s Identity): Let mn ( x) be the nth term of generalized Fibonacci-Like polynomials, then
mn2 x mn r x mn r x
1
nr
1 s mr x 2smr 1 x , n r 1.
1 5s 2
(3.16)
Proof. Using Binet’s formula (2.5), we have
mn2 x mn r x mn r x
An Bn A n r Bn r A n r Bn r
2
AB 1
AB 2 r r r r
n
nr
r
2
4s
1nr r r
2
4 s 2 1
nr
Since
r 2
r r
2
2
r r 1 s mr x 2smr 1 x 1 s mr x 2smr 1 x , we obtain
1 5s 2
1 s 2 2s1 s 4s 2
mn2 x mn r x mn r x
1
nr
1 s mr x 2smr 1 x , n r 1.
1 5s 2
Corollary 3.13 (Cassini’s Identity): Let mn ( x) be the nth term of generalized Fibonacci-Like polynomials, then
mn2 x mn 1 x mn 1 x 1
n 1
1 5s , n 1
2
(3.17)
Proof: If r = 1 in the Catalan’s identity, then obtained required result.
Theorem 3.14 (d’Ocagne’s Identity): Let mn(x) be the nth term of generalized Fibonacci-Like polynomials, then
n 1 s m p n x 2 sm p n 1
m p x mn1 x m p 1 x mn x 1
, p 1, n 0, p n.
1 5s 2
(3.18)
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Global Journal of Mathematical Analysis
Proof. Using the Binet’s formula (2.5), we have
mp x mn 1 x mp 1 x mn x A p B p An 1 Bn 1 A p 1 B p 1 An Bn ,
AB p n1 n1 p n p1 p1 n
AB
n
AB q
n
4s
2
p n
p n
p n
p n
,
p n
p n
1 p n p n ,
n
2
p n
pn
n
4s 2 1
.
Using subsequent results of Binet’s formula, we get
Since
p n p n 1 s m p n x 2sm p n 1 1 s m p n x 2sm p n 1 we obtain
,,
2
1 5s 2
1 s 2s 1 s 4s 2
n 1 s m p n x 2 sm p n 1
m p x mn 1 x m p 1 x mn x 1
, p 1, n 0, p n.
1 5s 2
Theorem 3.15 (Generalized Identity): Let mn ( x) be the nth term of generalized Fibonacci-Like polynomials,
then
p r
mp x mn x mp r x mnr x 1 1 s mr 2smr 1 1 s mn p r 2smn p r , n m r 1.
Proof. Using the Binet’s formula (2.5), we have
m p x mn1 x m p1 x mx n A p B p A n B n A pr B pr A nr B nr
p n n p
AB r r
r
r
AB
r
r
r
n r n r p
p
p n n p
AB r r r
r
AB 1
r
r
AB 1
r
p
AB 1
r
p
r p n r n r p
p
p
r
r
r
r
n p r
n p r
n p r
n p r
.
Using subsequent results of Binet’s formula, we get
Since
r r
1
1 s mr 2smr 1 .
1 5s 2
n p r n p r 1 s mn p r 2smn p r 1
,
1 5s 2
m p x mn x m pr x mnr x 1
p r
1 s mr 2smr 1 1 s mn pr 2smn pr , n m r 1
(3.19)
The identity (3.15) provides Catalan’s identity, Cassini and d’Ocagne and other identities:
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Global Journal of Mathematical Analysis
4. Conclusion
In this paper, Generalized Fibonacci-Like Polynomials are introduced. Some basic identities are generated and derived
by standard methods.
Acknowledgement
The authors are thankful to the reviewers for their constructive suggestions and comments for improving the exposition
of the original version.
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