The Heronian mean $H(a, b)$ is defined as $H(a, b) = \dfrac{a + \sqrt{ab} + b}{3} $. What is the least positive integer $b > 40$ such that $H(10, b)$ is also a positive integer?
The Heronian mean \(H(a, b)\) is defined as \(H(a, b) = \dfrac{a + \sqrt{ab} + b}{3}\). What is the least positive integer \(b > 40\) such that \(H(10, b)\) is also a positive integer?