1. Introduction and preliminaries
In this paper, we introduce the binomial transform of the generalized fifth
order Jacobsthal sequence and we investigate, in detail, two special cases
which we call them the binomial transform of the fifth order Jacobsthal and
fifth order Jacobsthal-Lucas sequences. We investigate their properties in
the next sections. In this section, we present some properties of the
generalized sequence (generalized Pentanacci) sequence.
The generalized sequence (the generalized Pentanacci sequence
or 5-step Fibonacci sequence)
is defined by the fifth-order recurrence relations
where the initial values are arbitrary
complex (or real) numbers and are real numbers. Pentanacci
sequence has been studied by many authors and more detail can be found in
the extensive literature dedicated to these sequences, see for example [
1,
2,
3,
4,
5]. The sequence can be extended to negative subscripts by defining
for Therefore, recurrence (1) holds
for all integer
As is a fifth order recurrence sequence (difference equation),
it’s characteristic equation is
whose roots are Note that we have
the following identities:
Generalized Pentanacci numbers can be expressed, for all integers using
Binet’s formula.
Theorem 1.
(Binet’s formula of generalized numbers (generalized
Pentanacci numbers))
where
Usually, it is customary to choose so that the Eq. (2) has at least one real (say ) solutions.
Eq. (3) can be written in the following form:
where
Next, we give the ordinary generating function of the sequence
Lemma 1.
Suppose that is the ordinary generating function of the generalized sequence
Then, is given by
We next find Binet formula of generalized numbers
by the use of generating function for
Theorem 2.
(Binet’s formula of generalized
numbers)
where
Matrix formulation of can be given as [
6]:
In fact, Kalman give the formula in the following
form
Next, we consider two special cases of the generalized
sequence which we call them and Lucas
sequences. sequence and Lucas sequence are defined, respectively, by
the fifth-order recurrence relations
The sequences and can be
extended to negative subscripts by defining
for respectively. Therefore, recurrences (7)
and (8) hold for all integers
For more details on the generalized numbers, see [4].
Some special cases of sequence and Lucas
sequence
are as follows:
- Pentanacci sequence,
- Pentanacci-Lucas sequence,
- fifth-order Pell sequence,
- fifth-order Pell-Lucas sequence.
For all integers and Lucas numbers (using
initial conditions in (3) or (5)) can
be expressed using Binet’s formulas as
respectively.
Lemma 1 gives the following results as particular
examples (generating functions of , Lucas and
modified numbers).
Corollary 1.
Generating functions of , Lucas and modified numbers are
respectively.
The following theorem shows that the generalized Pentanacci sequence
at negative indices can be expressed by the sequence itself at positive
indices.
Theorem 3.
For for the generalized
Pentanacci sequence (or generalized -sequence or 5-step
Fibonacci sequence) we have the following:
Proof.
For the proof, see [5], Theorem 1.
Using Theorem 3, we have the following corollary, see
[
5], Corollary 4.
Corollary 2.
For we have
Note that and can be given as follows by using
and in Theorem 3:
respectively.
Next, we consider the case and in this case we
write A generalized fifth order Jacobsthal sequence is
defined by the fifth order recurrence relations
with the initial values
not all being zero.
The sequence can be extended to negative subscripts by
defining
for Therefore, recurrence (9) holds
for all integer For more information on the generalized fifth order
Jacobsthal numbers, see [
7].
The first few generalized fifth order Jacobsthal numbers with positive
subscript and negative subscript are given in the Table 1
Table 1. A few generalized fifth order Jacobsthal numbers.
Eq. (3) can be used to obtain Binet’s formula of generalized
fifth order Jacobsthal numbers. Generalized fifth order Jacobsthal numbers
can be expressed, for all integers using Binet’s formula
where
As is a fifth order recurrence sequence (difference equation),
it’s characteristic equation is
The roots and of Eq. (10) are given by:
Note that we have the following identities:
Now we consider four special cases of the sequence . Fifth-order
Jacobsthal sequence , fifth order Jacobsthal-Lucas
sequence , adjusted fifth order Jacobsthal sequence and modified fifth order Jacobsthal-Lucas sequence are defined, respectively, by the fifth order
recurrence relations
The sequences , and can be extended to negative
subscripts by defining
for respectively. Therefore, recurrences (11)-(14) hold for all integer
Next, we present the first few values of the fifth order Jacobsthal, fifth
order Jacobsthal-Lucas, adjusted fifth order Jacobsthal and modified fifth
order Jacobsthal-Lucas numbers with positive and negative subscripts in the
following Table 2:
Table 2. The first few values of the special fifth order numbers with
positive and negative subscripts .
For all integers Binet formulas of fifth order Jacobsthal, fifth order
Jacobsthal-Lucas, adjusted fifth order Jacobsthal and modified fifth order
Jacobsthal-Lucas numbers are
respectively.
Binet formulas of fifth order Jacobsthal, fifth order Jacobsthal-Lucas,
adjusted fifth order Jacobsthal and modified fifth order Jacobsthal-Lucas
numbers can be given in the following forms:
Next, we give the ordinary generating function of the sequence
Lemma 2.
Suppose that is the ordinary generating function of the generalized
fifth order Jacobsthal sequence
Then, is given by
The previous Lemma gives the following results as particular examples:
generating function of the fifth order Jacobsthal, fifth order
Jacobsthal-Lucas, adjusted fifth order Jacobsthal and modified fifth order
Jacobsthal-Lucas are
respectively.
2. Binomial transform of the generalized fifth order Jacobsthal
sequence
In [
8], p. 137, Knuth introduced the idea of the binomial
transform. Given a sequence of numbers , its binomial transform may be defined by the rule
or, in the symmetric version
For more information on binomial transform, see, for example, [
9,
10,
11,
12]
and references therein. For recent works on binomial transform of well-known
sequences, see for example, [
13,
14,
15,
16,
17,
18,
19,
20,
21,
22,
23,
24,
25].
In this section, we define the binomial transform of the generalized fifth
order Jacobsthal sequence and as special cases the binomial
transform of the fifth order Jacobsthal, fifth order Jacobsthal-Lucas,
adjusted fifth order Jacobsthal and modified fifth order Jacobsthal-Lucas
sequences will be introduced.
Definition 1.
The binomial transform of the generalized fifth order Jacobsthal sequence is defined by
The few terms of are
Translated to matrix language, has the nice (lower-triangular
matrix) form
As special cases of , the binomial transforms of the
fifth order Jacobsthal and fifth order Jacobsthal-Lucas sequences are
defined as follows: The binomial transform of the fifth order Jacobsthal
sequence is
and the binomial transform of the fifth order Jacobsthal-Lucas sequence is
The binomial transform of the adjusted fifth order Jacobsthal sequence is
and the binomial transform of the modified fifth order Jacobsthal-Lucas
sequence is
Lemma 3.
For the binomial transform of the generalized fifth order
Jacobsthal sequence satisfies the following relation:
Proof.
We use the following well-known identity:
Note also that
Then
This completes the proof.
Remark 1.
From the Lemma 3, we see that
The following theorem gives recurrent relations of the binomial transform of
the generalized fifth order Jacobsthal sequence.
Theorem 4.
For the binomial transform of the generalized fifth order
Jacobsthal sequence satisfies the following recurrence relation:
Proof.
To show (15), writing
and taking the values and then solving the system of equations
we find that
The sequence can be extended to negative subscripts by
defining
for . Therefore, recurrence (15) holds
for all integer
Note that the recurence relation (15) is independent
from initial values. So,
The first few terms of the binomial transform of the generalized fifth order
Jacobsthal sequence with positive subscript and negative subscript are given
in the following Table 3.
Table 3. A few binomial transform (terms) of the generalized fifth order
Jacobsthal sequence.
The first few terms of the binomial transform numbers of the fifth order
Jacobsthal, fifth order Jacobsthal-Lucas, adjusted fifth order Jacobsthal
and modified fifth order Jacobsthal-Lucas sequences with positive subscript
and negative subscript are given in the following Table 4.
Table 4. A few binomial transform (terms).
Eq. (3) can be used to obtain Binet’s formula of the binomial
transform of generalized fifth order Jacobsthal numbers. Binet’s formula of
the binomial transform of generalized fifth order Jacobsthal numbers can be
given as
where
Here, and
are the roots of the equation
Moreover, the approximate value of and are given by
Note that
For all integers (Binet’s formulas of) binomial transforms of fifth
order Jacobsthal, fifth order Jacobsthal-Lucas, adjusted fifth order
Jacobsthal and modified fifth order Jacobsthal-Lucas numbers (using initial
conditions in (16)) can be expressed using Binet’s formulas
as
respectively.
3. Generating functions and obtaining Binet formula of binomial
transform from generating function
The generating function of the binomial transform of the generalized fifth
order Jacobsthal sequence is a power series centered at the origin
whose coefficients are the binomial transform of the generalized fifth order
Jacobsthal sequence.
Next, we give the ordinary generating function of the sequence
Lemma 4.
Suppose that is the ordinary generating function of the binomial transform
of the generalized fifth order Jacobsthal sequence
Then, is given by
Proof.
Using Lemma 1, we obtain
where
Note that P. Barry shows in [
26] that if is
the generating function of the sequence then
is the generating function of the sequence with In our case, since
we obtain
The Lemma 4 gives the following results as particular examples.
Corollary 3.
Generating functions of the binomial transform of the fifth order
Jacobsthal, fifth order Jacobsthal-Lucas, adjusted fifth order Jacobsthal
and modified fifth order Jacobsthal-Lucas numbers are
respectively.
4. Simson formulas
There is a well-known Simson Identity (formula) for Fibonacci sequence , namely,
which was derived first by R. Simson in 1753 and it is now called as Cassini
Identity (formula) as well. This can be written in the form
The following theorem gives generalization of this result to the generalized
Pentanacci sequence
Theorem 5.(Simson formula of generalized Pentanacci numbers)
For all integers we have
Proof.
Eq. (18) is given in [27], Theorem 3.1.
Taking in the above theorem and considering we have the following proposition.
Proposition 1.
For all integers Simson formula of binomial transforms of generalized
fifth order Jacobsthal numbers is given as
The Proposition 1 gives the following results as particular examples.
Corollary 4.
For all integers Simson formula of binomial transforms of the fifth
order Jacobsthal, fifth order Jacobsthal-Lucas, adjusted fifth order
Jacobsthal and modified fifth order Jacobsthal-Lucas numbers are given as
respectively.
5. Some identities
In this section, we obtain some identities of binomial transforms of fifth
order Jacobsthal, fifth order Jacobsthal-Lucas, adjusted fifth order
Jacobsthal and modified fifth order Jacobsthal-Lucas numbers. First, we
present a few basic relations between and .
Lemma 5.
The following equalities are true:
and
Proof.
Writing
and solving the system of equations
we find that
The other equalities can be proved similarly.
Now, we give a few basic relations between and .
Lemma 6.
The following equalities are true:
and
Next, we present a few basic relations between and .
Lemma 7.
The following equalities are true:
and
Now, we give a few basic relations between and .
Lemma 8.
The following equalities are true:
and
Next, we present a few basic relations between and .
Lemma 9.
The following equalities are true:
and
Now, we give a few basic relations between and .
Lemma 10.
The following equalities are true:
and
6. On the recurrence properties of binomial transform of the
generalized fifth order Jacobsthal sequence
Taking and in Theorem 3, we obtain the following Proposition.
Proposition 2.
For binomial Transform of the
generalized fifth order Jacobsthal sequence have the following identity:
Using Proposition 2 (and Corollary 2),
we obtain the following corollary which gives the connection between the
special cases of binomial transform of generalized fifth order Jacobsthal
sequence at the positive index and the negative index: for binomial
transform of fifth order Jacobsthal, fifth order Jacobsthal-Lucas numbers:
take with take with take with take with
respectively. Note that in this case we have . Note
also that .
Corollary 5.
For we have the following recurrence relations:
- (a) Recurrence relations of binomial transforms of fifth order
Jacobsthal numbers (take in Proposition 2):
- (b) Recurrence relations of binomial transforms of fifth order
Jacobsthal-Lucas numbers (take in Proposition 2):
- (c) Recurrence relations of binomial transforms of adjusted fifth
order Jacobsthal numbers (take in Proposition 2):
- (d) Recurrence relations of binomial transforms of modified fifth
order Jacobsthal-Lucas numbers (take in Proposition
2 or take in Corollary 2):
7. Sum formulas
7.1. Sums of terms with positive subscripts
The following proposition presents some formulas of binomial transform of
generalized fifth order Jacobsthal numbers with positive subscripts.
Proposition 3.
If then for we have the following
formulas:
Proof.
Take in Theorem 2.1 in [28].
From the last proposition, we have the following corollary which gives sum
formulas of binomial transform of fifth order Jacobsthal numbers (take with ).
Corollary 6.
For we have the following formulas:
Taking with in the last
proposition, we have the following corollary which presents sum formulas of
binomial transform of fifth order Jacobsthal-Lucas numbers.
Corollary 7.
For we have the following formulas:
From the last proposition, we have the following corollary which gives sum
formulas of binomial transform of adjusted fifth order Jacobsthal numbers
(take with ).
Corollary 8.
For we have the following formulas:
Taking with in the last
proposition, we have the following corollary which presents sum formulas of
binomial transform of modified fifth order Jacobsthal-Lucas numbers.
Corollary 9.
For we have the following formulas:
7.2. Sums of terms with negative subscripts
The following proposition presents some formulas of binomial transform of
generalized fifth order Jacobsthal numbers with negative subscripts.
Proposition 4.
If then for we have the following
formulas:
Proof.
Take in Theorem 3.1 in [28].
From the last proposition, we have the following corollary which gives sum
formulas of binomial transform of fifth order Jacobsthal numbers (take with
Corollary 10.
For binomial transform of fifth order Jacobsthal numbers have the
following properties.
Taking with in the last
proposition, we have the following corollary which presents sum formulas of
binomial transform of fifth order Jacobsthal-Lucas numbers.
Corollary 11.
For binomial transform of fifth order Jacobsthal-Lucas numbers
have the following properties.
From the last proposition, we have the following corollary which gives sum
formulas of binomial transform of adjusted fifth order Jacobsthal numbers
(take with ).
Corollary 12.
For binomial transform of adjusted fifth order Jacobsthal numbers
have the following properties.
Taking with in the last
proposition, we have the following corollary which presents sum formulas of
binomial transform of modified fifth order Jacobsthal-Lucas numbers.
Corollary 13.
For binomial transform of modified fifth order Jacobsthal-Lucas
numbers have the following properties.
8. Matrices related with binomial transform of generalized fifth order
Jacobsthal numbers
We define the square matrix of order as:
such that From (1) we have
and from (6) (or using (19) and
induction) we have
If we take in (19) we have
We also, for define
and
where
By convention, we assume that
Theorem 6.
For all integers we have
Proof.
- (a) Proof can be done by mathematical induction on
- (b) After matrix multiplication, (b) follows.
- (c) We have From the last equation, using
induction, we obtain Now
and similarly
Theorem 7.
For we have
Proof.
From the equation we see
that an element of is the product of row and a column From the last equation, we say that an element of is the
product of a row and column We just compare the linear
combination of the 2nd row and 1st column entries of the matrices
and . This completes the proof.
Corollary 14.
For we have
and
Author Contributions
All authors contributed equally to the writing of this paper. All authors read and approved the final manuscript.
Conflicts of Interest
The authors declare no conflict of interest.