# A163087 (b-file synthesized from sequence entry) 0 1 1 1 2 2 3 6 4 12 5 30 6 240 7 140 8 840 9 3780 10 15120 11 2772 12 221760 13 12012 14 960960 15 9266400 16 10810800 17 218790 18 7351344000 19 923780 20 16761064320 21 3259095840 22 3910915008 23 16224936 24 41977154419200 25 2028117000 26 249864014400