# A003498 (b-file synthesized from sequence entry)
0 1
1 12
2 48
3 252
4 1440
5 8544
6 52416
7 330588
8 2130240
9 13961808
10 92784384
11 623772288
12 4234688640
13 28990262016
14 199908428544
15 1387276513308
16 9681052037760
17 67895140257840
18 478281284627328
19 3382695596455344