# A145889 (b-file synthesized from sequence entry) 1 0 2 1 3 2 4 24 5 96 6 1080 7 6480 8 80640 9 645120 10 9072000 11 90720000 12 1437004800 13 17244057600 14 305124019200 15 4271736268800 16 83691159552000 17 1339058552832000 18 28810681675776000 19 518592270163968000 20 12164510040883200000