# A204265 (b-file synthesized from sequence entry)
1 2
2 2
3 9
4 40
5 144
6 1032
7 7824
8 48816
9 530712
10 5619456
11 50015232
12 707802624
13 9591229440
14 112586112000
15 1938416832000
16 32061464064000
17 469224244224000
18 9509523337728000
19 185772505605120000
20 3261008730405888000