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PEN Problems
PEN A Problems
88
88
Part of
PEN A Problems
Problems
(1)
A 88
Source:
5/25/2007
Find all positive integers
n
n
n
such that
9
n
ā
1
9^{n}-1
9
n
ā
1
is divisible by
7
n
7^n
7
n
.
induction
function
modular arithmetic
Divisibility Theory