# A370668 (b-file synthesized from sequence entry) 1 1 2 3 3 6 4 28 5 120 6 740 7 5040 8 40416 9 362898 10 3629400 11 39916800 12 479006070 13 6227020800 14 87178326480 15 1307674369200 16 20922790210656 17 355687428096000 18 6402373709004720 19 121645100408832000 20 2432902008212929224 21 51090942171709545840 22 1124000727778046764800