]> $$f\left(x;{\nu }_1,{\nu }_2;\lambda \right)=\sum _{k=0}^{\infty }\frac{e^{-\frac{\lambda }{2}}{\left(\frac{\lambda }{2}\right)}^k}{B\left(\frac{{\nu }_2}{\mathrm{2,}}\frac{{\nu }_1}{2}+k\right)k!}{\left(\frac{{\nu }_1}{{\nu }_2}\right)}^{\left(\frac{{\nu }_1}{2}+k\right)}{\left(\frac{{\nu }_2}{{\nu }_2+{\nu }_{1}x}\right)}^{\left(\frac{{\nu }_1+{\nu }_2}{2}+k\right)}{x}^{\left(\frac{{\nu }_1}{2}+k-1\right)}$$