permutations.RdReturns a matrix containing all permutations of the integers
1:n (one permutation per row).
permutations(n)permutations(3)
#> [,1] [,2] [,3]
#> [1,] 1 2 3
#> [2,] 2 1 3
#> [3,] 2 3 1
#> [4,] 1 3 2
#> [5,] 3 1 2
#> [6,] 3 2 1