# A013155 (b-file synthesized from sequence entry)
0 1
1 2
2 3
3 6
4 21
5 90
6 495
7 3150
8 23625
9 198450
10 1885275
11 19646550
12 225935325
13 2809456650
14 37927664775
15 547844046750
16 8491582724625
17 139700231921250
18 2444754058621875
19 45123174910563750
20 879901910755993125