# A345686 (b-file synthesized from sequence entry)
1 1
2 5
3 38
4 222
5 1974
6 14640
7 154580
8 1476720
9 17753400
10 205430400
11 2924030592
12 38559628800
13 623916216000
14 9701871379200
15 172359487872000
16 3007238402488320
17 60362232844193280
18 1161408374590464000
19 25603215951785472000
20 547592177551491072000
21 12990145748633044992000