# A268085 (b-file synthesized from sequence entry) 0 0 1 1 2 8 3 75 4 784 5 8820 6 104544 7 1288287 8 16359200 9 212751396 10 2821056160 11 38013731756 12 519227905728 13 7174705330000 14 100136810390400 15 1409850293610375 16 20002637245262400 17 285732116760449700 18 4106497099278420000 19 59341164471850545900 20 861753537765219528000