# A066631 (b-file synthesized from sequence entry) 1 4 2 8 3 24 4 120 5 840 6 9240 7 120120 8 2042040 9 38798760 10 1202761560 11 34880085240 12 802241960520 13 32891920381320 14 1414352576396760 15 52331045326680120 16 4657463034074530680 17 274790319010397310120 18 14563886907551057436360