Let a variable line passing through the centre of the circle $$x^2 + y^2 - 16x - 4y = 0$$, meet the positive coordinate axes at the point $$A$$ and $$B$$. Then the minimum value of $$OA + OB$$, where $$O$$ is the origin, is equal to

Center of circle $$x^2 + y^2 - 16x - 4y = 0$$ is $$(8, 2)$$.

Let the line intercepting positive axes be $$\frac{x}{a} + \frac{y}{b} = 1$$. Since it passes through $$(8, 2)$$, we get $$\frac{8}{a} + \frac{2}{b} = 1$$.

Expressing $$b = \frac{2a}{a-8}$$, the sum is $$S = a + b = a + \frac{2a}{a-8}$$.

Substituting $$u = a - 8$$, we get $$S = u + \frac{16}{u} + 10$$.

Applying AM-GM Inequality ($$u + \frac{16}{u} \ge 8$$), the minimum value is $$8 + 10 = 18$$.