/**
 * In probability theory and statistics, the negative binomial distribution is a
 * discrete probability distribution that models 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.
 * @param r number of failures
 * @param p probability
 */
export declare const negbin: (r: number, p: number) => number;