/ 2 \
\polygamma (0, x) + polygamma(1, x)/*Gamma(x)
$$\left(\operatorname{polygamma}^{2}{\left(0,x \right)} + \operatorname{polygamma}{\left(1,x \right)}\right) \Gamma\left(x\right)$$
/ 3 \
\polygamma (0, x) + 3*polygamma(0, x)*polygamma(1, x) + polygamma(2, x)/*Gamma(x)
$$\left(\operatorname{polygamma}^{3}{\left(0,x \right)} + 3 \operatorname{polygamma}{\left(0,x \right)} \operatorname{polygamma}{\left(1,x \right)} + \operatorname{polygamma}{\left(2,x \right)}\right) \Gamma\left(x\right)$$