Generalized Fibonacci Number
A generalization of the Fibonacci numbers defined by
and the recurrence relation
 |
(1)
|
These are the sums of elements on successive diagonals of a left-justified Pascal's triangle beginning in the leftmost column and moving in steps of
up and 1 right. The case
equals the usual Fibonacci number. These numbers satisfy the identities
 |
(2)
|
 |
(3)
|
 |
(4)
|
 |
(5)
|
(Bicknell-Johnson and Spears 1996). For the special case
,
 |
(6)
|
Bicknell-Johnson and Spears (1996) give many further identities.
Horadam (1965) defined the generalized Fibonacci numbers
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, where
,
,
, and
are integers,
,
, and
for
. They satisfy the identities
 |
(7)
|
 |
(8)
|
 |
(9)
|
 |
(10)
|
where
(Dujella 1996). The final above result is due to Morgado (1987) and is called the morgado identity.
Another generalization of the Fibonacci numbers is denoted
. Given
and
, define the generalized Fibonacci number by
for
,
 |
(13)
|
 |
(14)
|
 |
(15)
|
where the plus and minus signs alternate.
REFERENCES:
Bicknell, M. "A Primer for the Fibonacci Numbers, Part VIII: Sequences of Sums from Pascal's Triangle." Fib. Quart. 9, 74-81, 1971.
Bicknell-Johnson, M. and Spears, C. P. "Classes of Identities for the Generalized Fibonacci Numbers
for Matrices with Constant Valued Determinants." Fib. Quart. 34, 121-128, 1996.
Dujella, A. "Generalized Fibonacci Numbers and the Problem of Diophantus." Fib. Quart. 34, 164-175, 1996.
Horadam, A. F. "Generating Functions for Powers of a Certain Generalized Sequence of Numbers." Duke Math. J. 32, 437-446, 1965.
Horadam, A. F. "Generalization of a Result of Morgado." Portugaliae Math. 44, 131-136, 1987a.
Horadam, A. F. and Shannon, A. G. "Generalization of Identities of Catalan and Others." Portugaliae Math. 44, 137-148, 1987b.
Morgado, J. "Note on Some Results of A. F. Horadam and A. G. Shannon Concerning a Catalan's Identity on Fibonacci Numbers." Portugaliae Math. 44, 243-252, 1987.