# A261766 (b-file synthesized from sequence entry)
0 1
1 0
2 3
3 8
4 30
5 144
6 840
7 5760
8 45360
9 403200
10 3991680
11 43545600
12 518918400
13 6706022400
14 93405312000
15 1394852659200
16 22230464256000
17 376610217984000
18 6758061133824000
19 128047474114560000
20 2554547108585472000
21 53523844179886080000
22 1175091669949317120000