# A074002 (b-file synthesized from sequence entry)
1 0
2 0
3 6
4 6
5 30
6 72
7 252
8 756
9 2106
10 6642
11 19602
12 59292
13 176904
14 531441
15 1594323
16 4780782
17 14344533
18 43046721
19 129146724
20 387420489