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PEN Problems
PEN O Problems
18
18
Part of
PEN O Problems
Problems
(1)
O 18
Source:
5/25/2007
Let
p
p
p
be an odd prime number. How many
p
p
p
-element subsets
A
A
A
of
{
1
,
2
,
…
2
p
}
\{1,2,\ldots \ 2p\}
{
1
,
2
,
…
2
p
}
are there, the sum of whose elements is divisible by
p
p
p
?