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Putnam
2021 Putnam
B4
Putnam 2021 B4
Putnam 2021 B4
Source:
December 5, 2021
Putnam
Putnam 2021
Problem Statement
Let
F
0
,
F
1
,
…
F_0,F_1,\dots
F
0
,
F
1
,
…
be the sequence of Fibonacci numbers, with
F
0
=
0
,
F
1
=
1
F_0=0,F_1=1
F
0
=
0
,
F
1
=
1
, and
F
n
=
F
n
−
1
+
F
n
−
2
F_n=F_{n-1}+F_{n-2}
F
n
=
F
n
−
1
+
F
n
−
2
for
n
≥
2
n \ge 2
n
≥
2
. For
m
>
2
m>2
m
>
2
, let
R
m
R_m
R
m
be the remainder when the product
∏
k
=
1
F
m
−
1
k
k
\prod_{k=1}^{F_m-1} k^k
∏
k
=
1
F
m
−
1
k
k
is divided by
F
m
F_m
F
m
. Prove that
R
m
R_m
R
m
is also a Fibonacci number.
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