# A121735 (b-file synthesized from sequence entry)
1 1
2 -1
3 6
4 -12
5 -60
6 720
7 -2520
8 -20160
9 362880
10 -1814400
11 -19958400
12 479001600
13 -3113510400
14 -43589145600
15 1307674368000
16 -10461394944000
17 -177843714048000
18 6402373705728000
19 -60822550204416000
20 -1216451004088320000
21 51090942171709440000
22 -562000363888803840000