# A144884 (b-file synthesized from sequence entry)
0 1
1 3
2 21
3 123
4 792
5 5292
6 42768
7 348840
8 3313440
9 33734880
10 382423680
11 4683303360
12 62795865600
13 903908678400
14 14018003596800
15 231803919244800
16 4081121327001600
17 76062618390528000
18 1497060883196928000
19 31001124301830144000
20 673857550403702784000