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Problems
Contests
National and Regional Contests
Czech Republic Contests
Czech and Slovak Olympiad III A
2005 Czech And Slovak Olympiad III A
2
2
Part of
2005 Czech And Slovak Olympiad III A
Problems
(1)
2^{15} subsets X of {1,2,...,47}, min m in X, x in X, either x+m in X or x+m>47
Source: Czech and Slovak MO, III A, 2005 p2
1/12/2020
Determine for which
m
m
m
there exist exactly
2
15
2^{15}
2
15
subsets
X
X
X
of
{
1
,
2
,
.
.
.
,
47
}
\{1,2,...,47\}
{
1
,
2
,
...
,
47
}
with the following property:
m
m
m
is the smallest element of
X
X
X
, and for every
x
∈
X
x \in X
x
∈
X
, either
x
+
m
∈
X
x+m \in X
x
+
m
∈
X
or
x
+
m
>
47
x+m > 47
x
+
m
>
47
.
Subsets
combinatorics
minimum