# A025535 (b-file synthesized from sequence entry)
0 1
1 3
2 20
3 105
4 504
5 4620
6 51480
7 45045
8 1361360
9 23279256
10 21162960
11 446185740
12 2059318800
13 5736673800
14 155272637520
15 4512611027925
16 8494326640800
17 8022419605200
18 281206918792800
19 267146572853160
20 10431437606647200