# A124355 (b-file synthesized from sequence entry)
1 0
2 0
3 2
4 6
5 24
6 120
7 720
8 5040
9 40320
10 362880
11 3628800
12 39916800
13 479001600
14 6227020800
15 87178291200
16 1307674368000
17 20922789888000
18 355687428096000
19 6402373705728000
20 121645100408832000
21 2432902008176640000