# A355990 (b-file synthesized from sequence entry) 3 1 4 4 5 20 6 60 7 420 8 3360 9 10080 10 100800 11 1108800 12 3326400 13 43243200 14 605404800 15 1816214400 16 29059430400 17 494010316800 18 1482030950400 19 28158588057600 20 563171761152000 21 1689515283456000 22 37169336236032000 23 854894733428736000 24 2564684200286208000