(statistics) A discrete probability distribution of the number of successes in a sequence of independent and identically distributed Bernoulli trials before a specified (non-random) number of failures (denoted r) occurs.

In probability theory and statistics, the Poisson binomial distribution is the discrete probability distribution of a sum of independent Bernoulli trials that are not necessarily identically distributed.

In probability theory, a beta negative binomial distribution is the probability distribution of a discrete random variable  equal to the number of failures needed to get successes in a sequence of independent Bernoulli trials.