# A006678 (b-file synthesized from sequence entry)
0 0
1 1
2 1
3 6
4 39
5 390
6 4815
7 73080
8 1304415
9 26847450
10 625528575
11 16279193700
12 468022452975
13 14731683916950
14 503880434632575
15 18609309606888000
16 738057377647965375
17 31286068076704691250
18 1411602439003747365375
19 67543694966494692445500
20 3416288904242387117319375