# A119579 (b-file synthesized from sequence entry) 0 0 1 4 2 36 3 240 4 1400 5 7560 6 38808 7 192192 8 926640 9 4375800 10 20323160 11 93117024 12 421848336 13 1892909200 14 8424486000 15 37228204800 16 163493866080 17 714083503320 18 3103696272600 19 13431200244000 20 57895542104400 21 248675137991280