# A234294 (b-file synthesized from sequence entry) 0 1 1 1 2 4 3 40 4 664 5 15424 6 460576 7 16808320 8 724904896 9 36072438016 10 2034328297984 11 128223244372480 12 8932539799788544 13 681536817951791104 14 56521548341146402816 15 5062454448656689500160 16 487013865350356256137216 17 50082306316236214342844416 18 5482502331779770770018893824