# A058161 (b-file synthesized from sequence entry) 1 1 2 1 3 1 4 3 5 6 6 60 7 120 8 1260 9 6720 10 90720 11 362880 12 9979200 13 39916800 14 1037836800 15 10897286400 16 163459296000 17 1307674368000 18 59281238016000 19 355687428096000 20 15205637551104000 21 202741834014720000 22 5109094217170944000 23 51090942171709440000