# Parametrization of Pythagorean triplets

Fill the parentheses with a positive integer:

$3^2$ is a perfect square.

$3^2+4^2$ is a perfect square.

$3^2+4^2+12^2$ is a perfect square.

$3^2+4^2+12^2+ (\ \ \ \ )^2$ is a perfect square.

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