# A247591 (b-file synthesized from sequence entry)
0 1
1 1
2 3
3 16
4 126
5 1296
6 16071
7 228514
8 3607890
9 61891050
10 1135871490
11 22049362440
12 448790912004
13 9512960347260
14 208858963314735
15 4728736078065810
16 110006925920592810
17 2621619942885055530
18 63840054782606886630
19 1585094577104979776880
20 40054740803371374834780
21 1028483346608802276173280