# A108509 (b-file synthesized from sequence entry)
1 1
2 5
3 20
4 100
5 480
6 1980
7 7680
8 29040
9 100920
10 316320
11 923520
12 2502000
13 6011760
14 12584880
15 23417280
16 38196480
17 50112000
18 53667840
19 64988160
20 64988160