# A253901 (b-file synthesized from sequence entry)
1 1
2 1
3 2
4 6
5 24
6 60
7 720
8 840
9 20160
10 15120
11 3628800
12 55440
13 479001600
14 8648640
15 1816214400
16 259459200
17 20922789888000
18 147026880
19 6402373705728000
20 55870214400
21 1689515283456000
22 14079294028800
23 1124000727777607680000
24 771008958720
25 25852016738884976640000
26 32382376266240000
27 10002268381116211200000