# A013133 (b-file synthesized from sequence entry)
0 1
1 2
2 4
3 8
4 16
5 64
6 448
7 2816
8 14592
9 80896
10 705536
11 7278592
12 65245184
13 532070400
14 5385535488
15 71008190464
16 910402060288
17 10323887915008
18 124371776831488
19 1895043049717760
20 30930578556583936