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Brazil National Olympiad
2011 Brazil National Olympiad
4
Does there exist 2011 numbers?
Does there exist 2011 numbers?
Source: Brazil MO, Problem 4
October 20, 2011
number theory unsolved
number theory
Problem Statement
Do there exist
2011
2011
2011
positive integers
a
1
<
a
2
<
…
<
a
2011
a_1 < a_2 < \ldots < a_{2011}
a
1
<
a
2
<
…
<
a
2011
such that
gcd
(
a
i
,
a
j
)
=
a
j
−
a
i
\gcd(a_i,a_j) = a_j - a_i
g
cd
(
a
i
,
a
j
)
=
a
j
−
a
i
for any
i
i
i
,
j
j
j
such that
1
≤
i
<
j
≤
2011
1 \le i < j \le 2011
1
≤
i
<
j
≤
2011
?
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