# A068201 (b-file synthesized from sequence entry) 0 1 1 2 2 6 3 24 4 120 5 720 6 4920 7 37320 8 309120 9 2763720 10 26440920 11 268864320 12 2889978120 13 32689371720 14 387638491920 15 4803456571320 16 62026296732120 17 832595493624720 18 11592967532632920 19 167119530011233320 20 2489936579950221120 21 38283169922493447720