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Mathematics
Mathematics
Problem
List all pairs of positive integers
(
n
,
r
)
(n, r)
(
n
,
r
)
with
r
≤
n
2
r \le \dfrac{n}{2}
r
≤
2
n
that satisfy
n
C
r
=
210
{}^{n}C_{r} = 210
n
C
r
=
210
.
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