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Thailand Contests
Thailand Online MO
2023 Thailand Online MO
7
7
Part of
2023 Thailand Online MO
Problems
(1)
minimum of two consecutive terms is less than 1
Source: 2023 Thailand Online MO P7
2/12/2023
Let
a
0
,
a
1
,
…
a_0,a_1,\dots
a
0
,
a
1
,
…
be a sequence of positive reals such that
a
n
+
2
≤
2023
a
n
a
n
a
n
+
1
+
2023
a_{n+2} \leq \frac{2023a_n}{a_na_{n+1}+2023}
a
n
+
2
≤
a
n
a
n
+
1
+
2023
2023
a
n
for all integers
n
≥
0
n\geq 0
n
≥
0
. Prove that either
a
2023
<
1
a_{2023}<1
a
2023
<
1
or
a
2024
<
1
a_{2024}<1
a
2024
<
1
.
Inequality
algebra