$\begin{array}{l}Poisson(\theta )\frac{1}{x!}\theta {\text{e}}^{\theta }\\ Binomial(n,\theta )\left(\begin{array}{c}n\\ x\end{array}\right)\frac{\theta }{1+\theta }{\left(1+\theta \right)}^n\\ Logarithmic(\theta )\frac{1}{x}\theta -\ln \left(1-\theta \right)\\ Neg.Binomial\left(\begin{array}{c}k+x-1\\ x\end{array}\right)\theta {\left(1-\theta \right)}^{-k}\end{array}$