# A121636 (b-file synthesized from sequence entry)
1 0
2 1
3 5
4 23
5 122
6 754
7 5364
8 43308
9 391824
10 3929616
11 43287840
12 519711840
13 6755460480
14 94527008640
15 1416783432960
16 22646604153600
17 384576130713600
18 6914404440115200
19 131217341055897600
20 2621176954176614400