$$\frac{\delta {(\nu /2.)}^{1./2.}\Gamma ((\nu -1.)/2.)}{\Gamma (\nu /2.)}$$

$$\frac{\nu }{\left(\nu -2.\right)}(1.+{\delta }^{2.})-\frac{\nu }{2.}{\delta }^{2.}{\left[\frac{\Gamma ((\nu -1.)/2.)}{\Gamma (\nu /2.)}\right]}^{2.}$$