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2014 Saudi Arabia Pre-TST
1.3
1 - 5^n + 5^{2n+1} is a perfect square
1 - 5^n + 5^{2n+1} is a perfect square
Source: 2014 Saudi Arabia Pre-TST 1.3
September 13, 2020
number theory
Perfect Square
Problem Statement
Find all positive integers
n
n
n
for which
1
ā
5
n
+
5
2
n
+
1
1 - 5^n + 5^{2n+1}
1
ā
5
n
+
5
2
n
+
1
is a perfect square.
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