# A085687 (b-file synthesized from sequence entry) 0 1 1 6 2 36 3 224 4 1440 5 9504 6 64064 7 439296 8 3055104 9 21498880 10 152807424 11 1095450624 12 7911587840 13 57511157760 14 420459724800 15 3089600348160 16 22806128885760 17 169033661153280 18 1257467341701120 19 9385880636620800 20 70271680244613120 21 527595313582571520