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AoPS Wiki talk:Problem of the Day/July 4, 2011

Problem

AoPSWiki:Problem of the Day/July 4, 2011

Solution

$3^x-3 \equiv 0 \mod 16 \Rightarrow 3^x \equiv 3 \mod 16$.

So $3^x$ cycles through 3,9,11,1 mod 16, $x = 1$ doesn't work so try $x = 5$ which works and we're done.

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