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A new class of degenerate Hermite poly-Genocchi polynomials Waseem A. Khan1 and Nisar K S2

1Department of Mathematics, Faculty of Science, Integral University,

Lucknow-226026, India

2Department of Mathematics, College of Arts and Science-Wadi Al dawaser, Prince

Sattam bin Abdulaziz University, Riyadh region 11991, Saudi Arabia

E-mail: waseem08 khan@rediffmail.com, [email protected]

Abstract. In this article, authors introduce a new class of degenerate Hermite poly-Genocchi polynomials and give some identities of these polynomials related to the Stirling numbers of the second kind. Some implicit summation formulae and gen-eral symmetry identities are derived by using different analytical means and applying generating functions. These results extend some known summations and identities of degenerate Hermite poly-Bernoulli numbers and polynomials studied by Khan [8].

Keywords: Hermite polynomials, degenerate Hermite poly-Genocchi polynomials, summation formulae, symmetric identities.

2010 Mathematics Subject Classification.: 05A10, 05A15, 33C45, 33C99.

1. Introduction

The 2-variable Hermite-Kamp´e de F´eriet polynomials (2VHKdFP)Hn(x, y) [3, 5] are defined as

Hn(x, y) =n!

[n 2] ∑

r=0

yrxn−2r

r!(n−2r)!. (1.1)

From (1.1) is

ext+yt2 =

n=0

Hn(x, y)t n

n!. (1.2)

Wheny =1 and xis replaced by 2xin (1.2), the result reduces to ordinary Hermite polynomialsHn(x) (see [1]).

The generating function for degenerate Hermite polynomials are given by

(1 +λt)λx(1 +λt2) y λ =

n=0

Hn(x, y;λ)

tn

n!, (see [8]). (1.3)

where λ̸= 0. Since (1 +λt)λ1 −→et as λ−→ 0, it is evident that (1.3) reduces to

(1.2). That isHn(x, y) limiting case ofHn(x, y;λ) whenλ−→0.

By equating coefficients oftn on both the sides of (1.3), the following represen-tation ofHn(x, y;λ) is obtained

Hn(x, y;λ) =n!

[n 2] ∑

r=0

(−xλ)n2r(−yλ)r(−λ)n−r

r!(n−2r)! . (1.4)

Since limλ−→0Hn(x, y;λ) =Hn(x, y), (1.1) is a limiting case of (1.4).

The classical Genocchi numbersGn, the calssical Genocchi polynomialsGn(x) and the generalized Genocchi polynomilas G()(x) of (real or complex) orderα are

(2)

usually defined by means of the following generating functions (see for details[1], see also [8-14] and the references cited therein):

(

2t et+ 1

)

=

n=0 Gn

tn

n! (|t|< π), (1.5)

(

2t et+ 1

)α

ext=

n=0 G(nα)t

n

n! (|t|< π), (1.6)

and (

2t et+ 1

)α

ext=

n=0 G(nα)t

n

n! (|t|< π; 1

α= 1), (1.7)

with

G1n(0) = Gn(0) = Gn, (1.8) respectively.

Forλ∈C, Carlitz [4] introduced the degenerate Bernoulli polynomials defined by

t

(1 +λt)λ1 1

(1 +λt) =

n=0

βn(x;λ)t n

n!, (1.9)

so that

βn(x;λ) = m

n=0 (

n m

) βm(λ)(

x

λ)n−m. (1.10)

Whenx= 0,βn(λ) =βn(0;λ) are called the degenerate Bernoulli numbers. From (1.10), we note that

n=0

lim

λ−→0βn(x;λ) tn

n! = limλ−→0 t

(1 +λt)λ1 1

(1 +λt)

= t

et−1e xt

=

n=0 Bn(x)t

n

n!. (1.11)

whereBn(x) are called the Bernoulli polynomials (see [7-14]). The classical polylogarithm function Lik(z) is

Lik(z) =

m=1 zm

mk,(k∈Z) (see [6, 10-13]) (1.12)

so fork≤1,

Lik(z) =ln(1−z), Li0(z) = z

1−z, Li1(z) = z

(1−z)2, ...

The poly-Bernoulli polynomials are given by

Lik(1−e−t)

et1 e xt=

n=0

Bn(k)(x)t n

n!, (see [2, 10, 13]) (1.13)

Fork= 1 in (1.13), we have

Li1(1−e−t) et1 e

xt= t

et1e xt=

n=0 Bn(x)

tn

n!. (1.14)

From (1.13) and (1.14), we have

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Very recently, Khan [8] introduced the degenerate Hermite Bernoulli poly-nomials of two variables

(α)

n (x, y;λ) defined by

Lik(1−e−t) (1 +λt)λ1 1

(1 +λt)(1 +λt2) y λ =

n=0

Hβn(k)(x, y;λ)

tn

n!. (1.15)

Note that

lim λ−→0

Lik(1−e−t) (1 +λt)λ1 1

(1 +λt)(1 +λt2) y λ =

n=0

HBn(k)(x, y)

tn

n!. (1.16)

Fork= 1 in (1.16), the result reduces to known result of Dattoli et al. [5]. We recall the following definition as follows:

The Stirling number of the first kind is given by

(x)n =x(x−1)· · ·(x−n+ 1) = n

l=0

S1(n, l)xl,(n≥0). (1.17)

and the Stirling number of the second kind is defined by generating function to be

(et−1)n =n!

l=n

S2(l, n) tl

l!. (1.18)

A generalized falling factorial sum τk(n;λ) can be defined by the generating function [14]:

k=0

τk(n;λ)t k

k! =

1((1 +λt))(n+1)λ

1 + (1 +λt)λ1

. (1.19)

where limλ−→0τk(n;λ) =Tk(n).

In this paper, we consider a new class of degenerate Hermite Genocchi poly-nomialsHG

(k)

n,λ(x, y) and develop some elementary properties and derive some implicit formulae and symmetric identities for the degenerate Hermite poly-Genocchi polyno-mials by using different analytical means of their respective generating functions.

2. A new class of degenerate Hermite poly-Genocchi polynomials

Forλ∈C, k∈Z, we consider the degenerate Hermite poly-Genocchi polynomials which are given by the generating function

2Lik(1−e−t) (1 +λt)1λ + 1

(1 +λt)λx(1 +λt2) y λ =

n=0

HG

(k)

n,λ(x, y)

tn

n!, (2.1)

so that

HG

(k)

n,λ(x, y) = n

m=0 (

n m

)

G(m,λk)Hn−m(x, y;λ). (2.2)

Whenx=y= 0 in (2.1),G(n,λk) =HG

(k)

n,λ(0,0) are called the degenerate poly-Genocchi numbers. Note that

HG

(1)

n,λ(x, y) =HGn,λ(x, y), and

lim λ−→0HG

(k)

n,λ(x, y) =HG(nk)(x, y),(k∈Z). (2.3)

whereHG

(k)

(4)

Fory= 0 in (2.1), we have

2Lik(1−e−t) (1 +λt)λ1 + 1

(1 +λt) =

n=0

G(n,λk)(x)t n

n!,(λ∈C, k∈Z). (2.4)

Theorem 2.1. Forn≥0, we have

HG

(2)

n,λ(x, y) = n

m=0 (

n m

) Bmm!

m+ 1HGn−m,λ(x, y). (2.5)

Proof. Applying Definition (2.1), we have

n=0

HG(nk)(x, y;λ)

tn

n! =

2Lik(1−e−t) (1 +λt)λ1 + 1

(1 +λt)(1 +λt2) y λ

= 2(1 +λt)

x

λ(1 +λt2) y λ

(1 +λt)λ1 + 1 ∫ t

0

1

ez−1

t

0

1

ez−1 · · · 1

ez−1

t

0 z ez−1

| {z }

(k2)times

dz· · ·dz (2.6)

Fork= 2 in (2.6), we have

n=0

HG

(2)

n,λ(x, y)

tn

n! =

2(1 +λt)(1 +λt2) y λ

(1 +λt)1λ + 1 ∫ t

0 z ez1dz

=

(

m=0 Bmtm

m+ 1

)

2(1 +λt)(1 +λt2) y λ

(1 +λt)λ1 + 1

=

(

m=0 Bmm!

m+ 1

tm

m!

) (

n=0

HGn,λ(x, y)

tn

n!

)

Replacingnbyn−min above equation, we have

=

n=0 ( n

m=0 (

n m

) Bmm!

m+ 1HGn−m,λ(x, y)

) tn

n!.

On equating the coefficients of the like powers of tnn! in the above equation, we get the result (2.5).

Theorem 2.2. Forn≥0, we have

HG

(k)

n,λ(x, y) = n

p=0 (

n p

) (p+1

l=1

(1)l+p+1l!S

2(p+ 1, l) lk(p+ 1)

)

HGn−p,λ(x, y). (2.7)

Proof. From equation (2.1), we have

n=0

HG

(k)

n,λ(x, y)

tn

n! =

(

Lik(1−e−t)

t

) (

2t(1 +λt)(1 +λt2) y λ

(1 +λt)1λ + 1 )

(2.8)

Now

1

tLik(1−e

−t) = 1

t

l=1

(1−e−t)l

lk =

1

t

l=1

(1)l

lk (1−e

−t)l

=1

t

l=1

(1)l

lk l!

p=l

(1)pS2(p, l) tp p!

=1

t

p=1

p

l=1

(1)l+p

lk l!S2(p, l)

tp

(5)

=

p=0 (p+1

l=1

(1)l+p+1 lk l!

S2(p+ 1, l) p+ 1

) tp

p! (2.9)

From equations (2.8) and (2.9), we have

n=0

HG

(k)

n,λ(x, y)

tn n! =

p=0 (p+1

l=1

(1)l+p+1

lk l!

S2(p+ 1, l) p+ 1

) tp p!

(

n=0

HGn,λ(x, y)

tn n!

)

Replacingnbyn−pin the r.h.s of above equation and comparing the coefficients of tn

n!, we get the result (2.7).

Theorem 2.3. Forn≥1, we have HG

(k)

n,λ(x+ 1, y) +HG

(k)

n,λ(x, y)

= 2 n

p=1 (

n p

) (p1

l=0

(1)l+p+1

(l+ 1)k (l+ 1)!S2(p, l+ 1)

)

Hn−p(x, y;λ). (2.10)

Proof. Using the definition (2.1), we have

n=0

HG

(k)

n,λ(x+ 1, y)

tn

n!+

n=0

HG

(k)

n,λ(x, y)

tn

n!

=2Lik(1−e

−t)

(1 +λt)λ1 + 1

(1 +λt)x+1λ (1 +λt2) y

λ +2Lik(1−e

−t)

(1 +λt)λ1 + 1

(1 +λt)(1 +λt2) y λ

= 2Lik(1−e−t)(1 +λt)λx(1 +λt2) y λ

= 2

l=0

(1−e−t)l+1

(l+ 1)k (1 +λt)

x

λ(1 +λt2) y λ

= 2

p=1 (p1

l=0

(1)l+p+1

(l+ 1)k (l+ 1)!S2(p, l+ 1)

) tp

p!(1 +λt)

x

λ(1 +λt2) y λ

= 2

(

p=1 (p1

l=0

(1)l+p+1

(l+ 1)k (l+ 1)!S2(p, l+ 1)

) tp

p!

) (

n=0

Hn(x, y;λ)

tn

n!

)

Replacing n by n−p in the above equation and comparing the coefficients of tn

n!, we get the result (2.10).

Theorem 2.4. Forn≥0,d∈Nandk∈Z, we have

HG

(k)

n,λ(x, y) = d−1 ∑

a=0

n

l=0

l+1 ∑

p=1 (

n l

)

dn−l−1(1)

l+p+1p!S

2(l+ 1, p) pkl+ 1 HGn−l

( l+x

d , y; λ d

) .

(2.11)

Proof. From equation (2.1), we can be written as

n=0

HG

(k)

n,λ(x, y)

tn

n! =

2Lik(1−e−t) (1 +λt)λ1 + 1

(1 +λt)(1 +λt2) y λ

=2Lik(1−e

−t)

(1 +λt)λd + 1

d1 ∑

a=0

(1 +λt)l+λx(1 +λt2) y λ

=

(

Lik(1−e−t)

t )

1

d

d−1 ∑

a=0

2dt

(1 +λt)λd + 1

(6)

=

(

l=0 (l+1

p=1

(1)l+p+1 pk p!

S2(l+ 1, p) l+ 1

) tl

l!

) (

n=0 dn−1

d−1 ∑

a=0

HGn(

l+x d , y;

λ d)

tn

n!

) .

Replacingn byn−l in above equation and comparing the coefficient of tn

n!, we get

the result (2.11).

3. Implicit summation formulae involving degenerate Hermite poly-Genocchi polynomials

In this section, we establish some implicit summation formulae for degenerate Hermite poly-Genocchi polynomialsHG

(k)

n,λ(x, y) as follows.

Theorem 3.1. The following implicit summation formula involving degenerate Her-mite poly-Genocchi polynomialsHG

(k)

n,λ(x, y) holds true:

HG

(k)

n,λ(x+u, y+w) = n

m=0 (

n m

)

HG

(k)

n−m(x, y)Hm(u, w;λ). (3.1)

Proof. By the definition of degenerate poly-Genocchi polynomials and the definition (1.3), we have

2Lik(1−e−t) (1 +λt)1λ + 1

(1+λt)x+λu(1+λt2) y+w

λ = (

n=0

HG

(k)

n,λ(x, y)

tn

n!

) (

m=0

Hm(u, w;λ)t m

m!

)

Replacing nby n−min above equation and comparing the coefficients of tn n!,

we get the result (3.1).

Theorem 3.2. The following implicit summation formula involving degenerate Her-mite poly-Genocchi polynomialsHG

(k)

n,λ(x, y) holds true:

HG

(k)

n,λ(x, y) = n2j

m=0 [n

2] ∑

j=0

G(m,λk)(−x

λ)n−m−2j(−λ)

nmj(y

λ)j

n!

m!j!(n−2j−m)!.

(3.2)

Proof. Applying the definition (2.1) to the term 2Lik(1−e−t)

(1+λt)1λ+1 and expanding the

function (1 +λt)(1 +λt2) y

λ att= 0 yields

2Lik(1−e−t) (1 +λt)1λ + 1

(1+λt)(1+λt2) y λ =

(

m=0 G(m,λk) t

m

m!

) (

n=0

(−x

λ)n

(−λt)n

n!

)  ∑

j=0

(−y

λ)j

(−λt2)j

j!

 

=

n=0 ( n

m=0 (

n m

)

G(m,λk) (−x

λ)n−m(−λ)

n−m

) tn n!

 ∑

j=0

(−y

λ)j

(−λt2)j

j!

 

Replacingnbyn−2j, we have

n=0

HG

(k)

n,λ(x, y)

tn n!

=

n=0  n2j

m=0 [n

2] ∑

j=0 (

n−2j m

)

G(m,λk)(−x

λ)n−m−2j(−λ)

nmj(y

λ)j   tn

(n−2j)!j!.

(7)

Equating their coefficients of tnn!, we get the result (3.2).

Theorem 3.3. The following implicit summation formula involving degenerate Her-mite poly-Genocchi polynomialsHG

(k)

n,λ(x, y) holds true:

HG

(k)

n,λ(x, y) = n

m=0 (

n m

)

(−z

λ)n−m(−λ)

n−m HG

(k)

m,λ(x−z, y). (3.4)

Proof. By exploiting the generating function (2.1), we can write the equation

n=0

HG

(k)

n,λ(x, y)

tn

n! =

2Lik(1−e−t) (1 +λt)λ1 + 1

(1 +λt)x−λz(1 +λt2) y

λ(1 +λt) (3.5)

=

(

m=0

HG

(k)

m,λ(x−z, y)

tm

m!

) (

n=0

(−z

λ)n

(−λt)n

n!

)

Replacingnbyn−min above equation and equating their coefficients of tnn! leads to formula (3.4).

Theorem 3.4. The following implicit summation formula involving degenerate Her-mite poly-Genocchi polynomialsHG

(k)

n,λ(x, y) holds true:

HG

(k)

n,λ(x+ 1, y) = n

r=0 (

n r

)

(1

λ)r(−λ)

r HG

(k)

n−r,λ(x, y). (3.6)

Proof. By the definition of degenerate Hermite poly-Genocchi polynomials, we have

n=0

HG

(k)

n,λ(x+1, y)

tn

n!

n=0

HG

(k)

n,λ(x, y)

tn

n! =

2Lik(1−e−t) (1 +λt)1λ + 1

(1+λt)(1+λt2) y

λ((1+λt) 1 λ−1)

=

(

n=0

HG

(k)

n,λ(x, y)

tn

n!

) (

r=0

(1

λ)r

(−λt)r

r!

)

n=0

HG

(k)

n,λ(x, y)

tn

n!

=

n=0

n

r=0

HG

(k)

nr,λ(x, y)( 1

λ)r(−λ)

r t

n (n−r)!r!

n=0

HG

(k)

n,λ(x, y)

tn n!.

Finally, equating the coefficients of the like powers of tnn!, we get (3.6).

4. General symmetry identities for degenerate Hermite poly-Genocchi polynomials

In this section, we give general symmetry identities for the degenerate poly-Genocchi polynomialsG(n,λk)(x) and the degenerate Hermite poly-Genocchi polynomi-alsHG

(k)

n,λ(x, y) by applying the generating function(2.1) and (2.4).

Theorem 4.1. Leta, b >0 and=b. Forx, y∈Randn≥0, the following identity holds true:

n

m=0 (

n m

)

bman−mHG

(k)

nm,λ(bx, b

2y)HG(k)

m,λ(ax, a

2y)

= n

m=0 (

n m

)

ambn−mHG

(k)

n−m,λ(ax, a

2y)

HG

(k)

m,λ(bx, b

(8)

Proof. Let

g(t) =

(

2Lik(1−e−at)2Lik(1−e−bt) ((1 +λt) + 1)((1 +λt)

b λ + 1)

)

(1 +λt)abxλ (1 +λt2) a2b2y

λ . (4.2)

Then the expression for g(t) is symmetric in a and b and we can expand g(t) into series in two ways to obtain

g(t) =

n=0

HG

(k)

n,λ(bx, b

2y)(at)

n

n!

m=0

HG

(k)

m,λ(ax, a

2y)(bt)

m

m!

=

n=0 ( n

m=0 (

n m

)

an−mbmHG

(k)

n−m,λ(bx, b

2y)

HG

(k)

m,λ(ax, a

2y) )

tn

n!.

Similarly, we can show that

g(t) =

n=0

HG

(k)

n,λ(ax, a

2y)(bt)

n

n!

m=0

HG

(k)

m,λ(bx, b

2y)(at)

m

m!

=

n=0 ( n

m=0 (

n m

)

ambn−mHG

(k)

nm,λ(ax, a

2y)HG(k)

m,λ(bx, b

2y) )

tn n!.

Comparing the coefficients of tnn! on the right hand sides of the last two equations, we arrive the desired result.

Remark 1. On settingb = 1 in Theorem 4.1, we get the following result n

m=0 (

n m

)

an−mHG

(k)

n−m,λ(x, y)HG

(k)

m,λ(ax, a

2y)

= n

m=0 (

n m

) amHG

(k)

nm,λ(ax, a

2y)HG(k)

m,λ(x, y). (4.3)

Theorem 4.2. For all integers a >0, b >0, andn≥0, the following identity holds true:

n

m=0 (

n m

)

an−mbmHG

(k)

n−m,λ

( bx, b2z)

m

i=0 (

m i

)

τi(a−1;λ)Gm(k)i,λ(ay)

= n

m=0 (

n m

)

ambn−mHG

(k)

nm,λ

(

ax, a2z)

m

i=0 (

m i

)

τi(b−1;λ)G(mk)i,λ(by). (4.4)

where generalized falling factorial sumτk(n;λ) is given by (1.19).

Proof. We now use

g(t) = 2Lik(1−e

−at)2Lik(1ebt)(1((1 +λt))ab

λ)(1 +λt) ab(x+y)

λ (1 +λt2) a2b2z

λ

((1 +λt) + 1)((1 +λt)λb + 1)2

to find that

g(t) =

(

2Lik(1−e−at) (1 +λt) + 1

)

(1 +λt)abxλ (1 +λt2) a2b2z

λ (

1((1 +λt))abλ

(1 +λt)λb + 1 )

(

2Lik(1−e−bt) (1 +λt)λb + 1

)

(1 +λt)abyλ

=

n=0

HG

(k)

n,λ

(

bx, b2z)(at)

n

n!

n=0

τn(a−1;λ) (bt)n

n!

n=0

G(n,λk)(ay)(bt) n

(9)

=

n=0

HG

(k)

n,λ

(

bx, b2z)(at)

n

n!

m=0

m

i=0 (

m i

)

bmτi(a−1;λ)G

(k)

m−i,λ(ay)

tm

m!

=

n=0 ( n

m=0 (

n m

)

an−mbmHG

(k)

n−m,λ

( bx, b2z)

m

i=0 (

m i

)

τi(a−1;λ)G

(k)

m−i,λ(ay)

) tn

n!. (4.5) By using a similar plan, we get

g(t) =

n=0 ( n

m=0 (

n m

)

ambn−mHG

(k)

n−m,λ

(

ax, a2z)

m

i=0 (

m i

)

τi(b−1;λ)Gm(k)i,λ(by)

) tn n!.

(4.6) After comparing the coefficients of tnn! on the right hand sides of the last two equa-tions, we arrive at the desired result.

References

[1] Andrews, L. C, Special functions for engineers and mathematicians, Macmil-lan Co. New York, 1985.

[2] Bayad, A, Hamahata, Y, Multiple-Polylogarithms and multi-poly-Bernoulli polynomials, Funct. Approx. Comment. Math., 45(2012), 45-61.

[3] Bell, E. T, Exponential polynomials, Ann. of Math., 35(1934), 258-277. [4] Carlitz, L, Degenerate Stirling Bernoulli and Eulerian numbers, Util. Math.,

15(1979), 51-88.

[5] Dattoli, G, Lorenzutta, S and Cesarano, C, Finite sums and generalized forms of Bernoulli polynomials, Rendiconti di Mathematica, 19(1999), 385-391. [6] Jolany, H, Mohebbi, H, Some results on generalized multi-poly Bernoulli and

Euler polynomials, Int. J. Math. Comb., 2(2011), 117-129.

[7] Kaneko, M, Poly-Bernoulli numbers, J. de Theorie de Nombres 9 (1997), 221-228.

[8] Khan W. A, A note on degenerate Hermite Bernoulli numbers and poly-nomials, Journal of Classical Anal., 8(1)(2016), 65-76.

[9] Khan W. A, A new class of Hermite poly-Genocchi polynomials, J. Anal. Numb. Theor., 4(1)(2016), 1-8.

[10] Kim, T, Kwon, H. I, Lee, S. H and Seo, J. J, A note on poly-Bernoulli numbers and Polynomials of the second kind, Adv. Differen. Equations, 2014, 2014:219.

[11] Kim, D. S and Kim, T, A note on degenerate poly-Bernoulli numbers and polynomials, Advan. Diff. Equat., DOI 10.1186/s13662-015-0595-3, (2015). [12] Kim, D. S, Dolgy, D. V and Komatsu, T, Barnes type degenerate Bernoulli

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[13] Kim, T, Barnes type multiple degenerate Bernoulli and Euler polynomials, Appl. Math. Comput., 258(2015), 556-564.

References

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