# A109388 (b-file synthesized from sequence entry) 0 1 1 2 2 4 3 12 4 32 5 80 6 240 7 672 8 1792 9 5376 10 15360 11 42240 12 126720 13 366080 14 1025024 15 3075072 16 8945664 17 25346048 18 76038144 19 222265344 20 635043840 21 1905131520 22 5588385792 23 16066609152 24 48199827456 25 141764198400 26 409541017600 27 1228623052800 28 3621204787200