# A097171 (b-file synthesized from sequence entry)
1 1
2 1
3 6
4 24
5 320
6 3270
7 55482
8 999656
9 21718440
10 544829130
11 15130478990
12 475440344412
13 16294653237876
14 613546243029902
15 25016884214147490
16 1100408748640263120
17 51948228453097163312
18 2617775548597611727506
19 140364712844785892810646
20 7975414423897012183673540