# A336310 (b-file synthesized from sequence entry) 0 0 1 0 2 2 3 24 4 300 5 4260 6 69120 7 1271340 8 26233200 9 601246800 10 15171105600 11 418203324000 12 12509695598400 13 403696590897600 14 13982667790291200 15 517482647165484000 16 20381726051118432000 17 851302665544050720000 18 37587618060140244096000 19 1749369290830388555328000 20 85599487854917373617280000