# A069660 (b-file synthesized from sequence entry)
3 6
4 8
5 120
6 72
7 5040
8 1152
9 362880
10 28800
11 39916800
12 1036800
13 6227020800
14 50803200
15 1307674368000
16 3251404800
17 355687428096000
18 263363788800
19 121645100408832000
20 26336378880000
21 51090942171709440000