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National and Regional Contests
Netherlands Contests
Dutch Mathematical Olympiad
2023 Dutch Mathematical Olympiad
2
2
Part of
2023 Dutch Mathematical Olympiad
Problems
(1)
2023 vases numbered from 1 to 2023, and 2023 notes
Source: Netherlands - Dutch NMO 2023 p2
3/25/2024
In a room there are
2023
2023
2023
vases numbered from
1
1
1
to
2023
2023
2023
. In each vase we want to put a note with a positive integer from
1
1
1
,
2
2
2
.
.
.
...
...
,
2023
2023
2023
on it. The numbers on the notes do not necessarily have to be distinct. The following should now apply to each vase. Look at the note inside the vase, find the (not necessarily different) vase with the number written on the note, and look at the note inside this vase. Then the average of the numbers on the two notes must be exactly equal to the number of the first selected vase. For example, if we put a note with the number
5
5
5
in vase
13
13
13
, then vase
5
5
5
should contain a note with the number
21
21
21
on it: after all, the average of
5
5
5
and
21
21
21
is
13
13
13
. Determine all possible ways to provide each vase with a note.
combinatorics