# A240921 (b-file synthesized from sequence entry)
0 1
1 1
2 3
3 18
4 146
5 1530
6 19620
7 297360
8 5201784
9 103146120
10 2286181800
11 56011087440
12 1503057473280
13 43844234353920
14 1381310964633600
15 46743301840435200
16 1690919874777893760
17 65116170597269151360
18 2659604669692822051200
19 114838104572526535200000
20 5226654647185285702752000