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MathLinks Contest 1st
3
0163 Fibonacci 1st edition Round 6 p3
0163 Fibonacci 1st edition Round 6 p3
Source:
May 9, 2021
number theory
1st edition
Problem Statement
Consider
(
f
n
)
n
≥
0
(f_n)_{n\ge 0}
(
f
n
)
n
≥
0
the Fibonacci sequence, defined by
f
0
=
0
f_0 = 0
f
0
=
0
,
f
1
=
1
f_1 = 1
f
1
=
1
,
f
n
+
1
=
f
n
+
f
n
−
1
f_{n+1} = f_n + f_{n-1}
f
n
+
1
=
f
n
+
f
n
−
1
for all positive integers
n
n
n
. Solve the following equation in positive integers
n
f
n
f
n
+
1
=
(
f
n
+
2
−
1
)
2
.
nf_nf_{n+1} = (f_{n+2} - 1)^2.
n
f
n
f
n
+
1
=
(
f
n
+
2
−
1
)
2
.
.
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