# A375224 (b-file synthesized from sequence entry) 0 1 1 2 2 8 3 54 4 492 5 5400 6 68520 7 987000 8 15928080 9 284588640 10 5570994240 11 118432147680 12 2714315123520 13 66662973336960 14 1745585471710080 15 48522632817859200 16 1426443527673964800 17 44200671544495065600 18 1439417651948346470400 19 49134301244829555955200