code: public static PermutationGroup makeSymN(int size) {
          List<Permutation> generators = new ArrayList<Permutation>();
  
          // p1 is (0, 1)
          int[] p1 = new int[size];
          p1[0] = 1;
          p1[1] = 0;
          for (int i = 2; i < size; i++) {
              p1[i] = i;
          }
  
          // p2 is (1, 2, ...., n, 0)
          int[] p2 = new int[size];
          p2[0] = 1;
          for (int i = 1; i < size - 1; i++) {
              p2[i] = i + 1;
          }
          p2[size - 1] = 0;
  
          generators.add(new Permutation(p1));
          generators.add(new Permutation(p2));
  
          return new PermutationGroup(size, generators);
      }
docs: Make the symmetric group Sym(N) for N. That is, a group of permutations
  that represents _all_ permutations of size N.
  
  @param size the size of the permutation
  @return a group for all permutations of N