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Iran MO (3rd Round)
2002 Iran MO (3rd Round)
14
14
Part of
2002 Iran MO (3rd Round)
Problems
(1)
Eventually linear
Source: Iranian National Olympiad (3rd Round) 2002
10/2/2006
A subset
S
S
S
of
N
\mathbb N
N
is eventually linear iff there are
k
,
N
∈
N
k,N\in\mathbb N
k
,
N
∈
N
that for
n
>
N
,
n
∈
S
⟺
k
∣
n
n>N,n\in S\Longleftrightarrow k|n
n
>
N
,
n
∈
S
⟺
k
∣
n
. Let
S
S
S
be a subset of
N
\mathbb N
N
that is closed under addition. Prove that
S
S
S
is eventually linear.
number theory proposed
number theory