Combinatorics
Index oW: without repetition; Index mW: with repetition. Category.
Category. permutations
1. Number of permutations of n different elements
B. Combinations (regardless of the arrangement)
1. Number of combinations of k elements from n different elements or. Number of k -subsets from an n-set
C. Variations (taking into account the arrangement)
1. Number of variations of each k elements from n different elements without repetition of the elements or. Number of k-permutations from an n-set