# A277407 (b-file synthesized from sequence entry)
0 1
1 1
2 3
3 19
4 220
5 4196
6 120876
7 4915212
8 268194816
9 18903020544
10 1671209210880
11 181064295924480
12 23589442167333120
13 3638090042721918720
14 655483159341216541440
15 136420837710333144595200
16 32478481518550347674419200
17 8770206330674425311097651200
18 2666047809138871800854163456000
19 906320525390421790143785781657600
20 342508343836409428996994343026688000