# A052581 (b-file synthesized from sequence entry) 0 1 1 0 2 0 3 0 4 24 5 120 6 720 7 5040 8 80640 9 1088640 10 14515200 11 199584000 12 3353011200 13 62270208000 14 1220496076800 15 24845812992000 16 543992537088000 17 12804747411456000 18 320118685286400000 19 8393511928209408000