# A123071 (b-file synthesized from sequence entry)
0 1
1 2
2 4
3 12
4 36
5 120
6 400
7 1520
8 5776
9 23712
10 97344
11 431808
12 1915456
13 9012608
14 42406144
15 210988800
16 1049760000
17 5475340800
18 28558296064
19 155672726528
20 848579961856
21 4810614454272
22 27271456395264
23 160376430784512
24 943132599095296
25 5735299537018880