# A007905 (b-file synthesized from sequence entry)
0 0
1 0
2 1
3 4
4 30
5 216
6 1440
7 11040
8 112560
9 1229760
10 14333760
11 179988480
12 2259290880
13 30656102400
14 446269824000
15 6949355212800
16 123855443712000
17 2320686111744000
18 45616912653312000
19 939726185029632000
20 20166054423330816000