What equation can I use to calculate escape velocity as the radius increases from the Schwarzschild radius?

As follows from energy conservation, the gravitational time dilation near a Schwarzschild object is equal to the velocity time dilation at the escape speed:

$$dfrac{tau}{t}=sqrt{1-dfrac{r_s}{r}}=sqrt{1-dfrac{v^2}{c^2}}$$

$$v=csqrt{dfrac{r_s}{r}}$$

$$v=sqrt{dfrac{2GM}{r}}$$

Where $c$ is the speed of light, $G$ is the gravitational constant, $M$ is the mass of the object, and $r_s$ is the Schwarzschild radius. Due to energy conservation, this result is the same for the Newtonian gravity.