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Contests
National and Regional Contests
Switzerland Contests
Switzerland Team Selection Test
2023 Switzerland Team Selection Test
2
2
Part of
2023 Switzerland Team Selection Test
Problems
(1)
NT with a set
Source: Swiss TST 2023 P2
9/8/2023
Let
S
S
S
be a non-empty set of positive integers such that for any
n
∈
S
n \in S
n
∈
S
, all positive divisors of
2
n
+
1
2^n+1
2
n
+
1
are also in
S
S
S
. Prove that
S
S
S
contains an integer of the form
(
p
1
p
2
…
p
2023
)
2023
(p_1p_2 \ldots p_{2023})^{2023}
(
p
1
p
2
…
p
2023
)
2023
, where
p
1
,
p
2
,
…
,
p
2023
p_1, p_2, \ldots, p_{2023}
p
1
,
p
2
,
…
,
p
2023
are distinct prime numbers, all greater than
2023
2023
2023
.
number theory