# A023199 (b-file synthesized from sequence entry) 1 1 2 6 3 120 4 27720 5 122522400 6 130429015516800 7 1970992304700453905270400 8 1897544233056092162003806758651798777216000 9 4368924363354820808981210203132513655327781713900627249499856876120704000