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Poland Contests
Polish MO Finals
1998 Polish MO Finals
2
Fibonacci and another sequence
Fibonacci and another sequence
Source:
November 11, 2005
induction
number theory unsolved
number theory
Problem Statement
F
n
F_n
F
n
is the Fibonacci sequence
F
0
=
F
1
=
1
F_0 = F_1 = 1
F
0
=
F
1
=
1
,
F
n
+
2
=
F
n
+
1
+
F
n
F_{n+2} = F_{n+1} + F_n
F
n
+
2
=
F
n
+
1
+
F
n
. Find all pairs
m
>
k
≥
0
m > k \geq 0
m
>
k
≥
0
such that the sequence
x
0
,
x
1
,
x
2
,
.
.
.
x_0, x_1, x_2, ...
x
0
,
x
1
,
x
2
,
...
defined by
x
0
=
F
k
F
m
x_0 = \frac{F_k}{F_m}
x
0
=
F
m
F
k
and
x
n
+
1
=
2
x
n
−
1
1
−
x
n
x_{n+1} = \frac{2x_n - 1}{1 - x_n}
x
n
+
1
=
1
−
x
n
2
x
n
−
1
for
x
n
≠
1
x_n \not = 1
x
n
=
1
, or
1
1
1
if
x
n
=
1
x_n = 1
x
n
=
1
, contains the number
1
1
1
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