# A058583 (b-file synthesized from sequence entry)
0 1
1 1
2 2
3 6
4 36
5 240
6 2040
7 21000
8 235200
9 3265920
10 47628000
11 795175920
12 14411295360
13 279281882880
14 6049083680640
15 135398783520000
16 3367873821312000
17 87219462185856000
18 2403098895060864000
19 70681813184753971200
20 2138850761148310809600