# A200978 (b-file synthesized from sequence entry) 3 6 4 72 5 720 6 7200 7 75600 8 846720 9 10160640 10 130636800 11 1796256000 12 26345088000 13 410983372800 14 6799906713600 15 118998367488000 16 2196892938240000 17 42682491371520000 18 870722823979008000 19 18611700362551296000 20 416026243398205440000