# Combinatorics

Permutation Calculate the number of permutations of a set of n elements.

Arrangement Calculation of the number of p element arrangements among a set of n elements.

Combination Calculate the number of combinations of p elements among a set of n elements.

Binomial coefficient Calculation of the binomial coefficient.

Multinomial coefficient Calculation of multinomial coefficients and Newton's multinomial formula.

Catalan number Calculation of the Catalan numbers.

Lah numbers Calculation of Lah numbers.

Derangement Calculate the number of derangements of k elements from a set of n elements.

Factorial Calculate number factorial