For what values of k given below is $${{{{\left( {k + 2} \right)}^2}} \over {k - 3}}$$ an integer?

Functions F(a, b) and G(a, b) are defined as follows:
F(a, b) = (a - b)² and G(a, b) = |a - b| , where |x| represents the absolute value of x.
What would be the value of G(F(1, 3), G(1, 3))?