Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The Panjer recursion is an algorithm to compute the probability distribution of a compound random variablewhere both N, and X_i, are stochastic and of a special type. It was introduced in a paper of Harry Panjer . It is heavily used in actuarial science.Sundt proved in the paper that only the binomial distribution, the Poisson distribution and the negative binomial distribution belong to the Panjer class, depending on the sign of a,. They have the parameters and values as described in the following table. W_N(x), denotes the probability generating function.