# A375395 (b-file synthesized from sequence entry) 0 1 1 1 2 2 3 7 4 32 5 180 6 1210 7 9520 8 85680 9 867160 10 9749600 11 120582000 12 1626994600 13 23782158400 14 374367193200 15 6314037129400 16 113591474796800 17 2171267969270400 18 43944509528920000 19 938808209417478400 20 21111813400597920000 21 498498097342637392000