$ ./derangements.pl 4
2,3,0,1: 11.08% (expected -0.03%)
1,0,3,2: 11.09% (expected -0.02%)
2,3,1,0: 11.10% (expected -0.01%)
1,3,0,2: 11.11% (expected -0.01%)
2,0,3,1: 11.11% (expected -0.00%)
1,2,3,0: 11.12% (expected +0.01%)
3,0,1,2: 11.12% (expected +0.01%)
3,2,1,0: 11.13% (expected +0.02%)
3,2,0,1: 11.14% (expected +0.03%)
Total 9 (1000000 runs)