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National and Regional Contests
PEN Problems
PEN A Problems
15
A 15
A 15
Source:
May 25, 2007
number theory
least common multiple
Divisibility Theory
pen
Problem Statement
Suppose that
k
≥
2
k \ge 2
k
≥
2
and
n
1
,
n
2
,
⋯
,
n
k
≥
1
n_{1}, n_{2}, \cdots, n_{k}\ge 1
n
1
,
n
2
,
⋯
,
n
k
≥
1
be natural numbers having the property
n
2
∣
2
n
1
−
1
,
n
3
∣
2
n
2
−
1
,
⋯
,
n
k
∣
2
n
k
−
1
−
1
,
n
1
∣
2
n
k
−
1.
n_{2}\; \vert \; 2^{n_{1}}-1, n_{3}\; \vert \; 2^{n_{2}}-1, \cdots, n_{k}\; \vert \; 2^{n_{k-1}}-1, n_{1}\; \vert \; 2^{n_{k}}-1.
n
2
∣
2
n
1
−
1
,
n
3
∣
2
n
2
−
1
,
⋯
,
n
k
∣
2
n
k
−
1
−
1
,
n
1
∣
2
n
k
−
1.
Show that
n
1
=
n
2
=
⋯
=
n
k
=
1
n_{1}=n_{2}=\cdots=n_{k}=1
n
1
=
n
2
=
⋯
=
n
k
=
1
.
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