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5
2n+7 | n! -1
2n+7 | n! -1
Source: Turkey JBMO Team Selection Test 2013, P6
May 31, 2013
modular arithmetic
number theory
number theory proposed
Problem Statement
Find all positive integers
n
n
n
satisfying
2
n
+
7
∣
n
!
−
1
2n+7 \mid n! -1
2
n
+
7
∣
n
!
−
1
.
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