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