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PEN Problems
PEN S Problems
28
28
Part of
PEN S Problems
Problems
(1)
S 28
Source:
5/25/2007
Let
A
A
A
be the set of the
16
16
16
first positive integers. Find the least positive integer
k
k
k
satisfying the condition: In every
k
k
k
-subset of
A
A
A
, there exist two distinct
a
,
b
ā
A
a, b \in A
a
,
b
ā
A
such that
a
2
+
b
2
a^2 + b^2
a
2
+
b
2
is prime.
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