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Problems
Contests
National and Regional Contests
PEN Problems
PEN E Problems
28
28
Part of
PEN E Problems
Problems
(1)
E 28
Source:
5/25/2007
Show that
n
π
(
2
n
)
−
π
(
n
)
<
4
n
n^{\pi(2n)-\pi(n)}<4^{n}
n
π
(
2
n
)
−
π
(
n
)
<
4
n
for all positive integer
n
n
n
.