# A096121 (b-file synthesized from sequence entry) 1 2 2 8 3 60 4 816 5 17520 6 550080 7 23839200 8 1365799680 9 100053999360 10 9127781913600 11 1015061950425600 12 135193044668774400 13 21248464632595200000 14 3891825697262043340800 15 821745573997874093568000 16 198152975926832672858112000 17 54121124248225908770856960000 18 16621698830590738881776812032000