# A344273 (b-file synthesized from sequence entry) 1 1 2 6 3 24 4 80 5 273 6 960 7 3336 8 11480 9 39648 10 136952 11 472416 12 1630164 13 5625480 14 19412736 15 66992016 16 231184800 17 797806152 18 2753187210 19 9501109380 20 32787848746