# A115506 (b-file synthesized from sequence entry) 1 1 2 2 3 6 4 8 5 24 6 168 7 840 8 1008 9 4032 10 32160 11 192960 12 1297440 13 9082080 14 126846720 15 1141620480 16 1243468800 17 4490307360 18 53812332000 19 526257365760 20 3736568586240 21 33629117276160 22 539852417395200 23 5938376591347200 24 43328496719692800 25 612865454506905600 26 12864962752408166400 27 204270526971128217600 28 2666714307922074009600 29 40000714618831110144000