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International Contests
APMO
2021 APMO
2
2
Part of
2021 APMO
Problems
(1)
Bounding Divisibility
Source: 2021 APMO P2
6/9/2021
For a polynomial
P
P
P
and a positive integer
n
n
n
, define
P
n
P_n
P
n
as the number of positive integer pairs
(
a
,
b
)
(a,b)
(
a
,
b
)
such that
a
<
b
≤
n
a<b \leq n
a
<
b
≤
n
and
∣
P
(
a
)
∣
−
∣
P
(
b
)
∣
|P(a)|-|P(b)|
∣
P
(
a
)
∣
−
∣
P
(
b
)
∣
is divisible by
n
n
n
. Determine all polynomial
P
P
P
with integer coefficients such that
P
n
≤
2021
P_n \leq 2021
P
n
≤
2021
for all positive integers
n
n
n
.
algebra
polynomial