# A357257 (b-file synthesized from sequence entry) 5 240 6 2880 7 33600 8 403200 9 5093760 10 68275200 11 972787200 12 14724864000 13 236396160000 14 4016659046400 15 72067387392000 16 1362306097152000 17 27071765360640000 18 564357385912320000 19 12317692759916544000 20 280955128203509760000