# A354309 (b-file synthesized from sequence entry) 0 1 1 0 2 2 3 6 4 44 5 360 6 3744 7 46200 8 662864 9 10838016 10 198943200 11 4050937440 12 90613710912 13 2208677328000 14 58265734055424 15 1653914478303360 16 50263564166365440 17 1628300694034022400 18 56012708047907510784 19 2039053421375533094400 20 78314004507947110456320