# A002711 (b-file synthesized from sequence entry)
0 1
1 5
2 21
3 119
4 735
5 4830
6 33253
7 237336
8 1743588
9 13114465
10 100591491
11 784428522
12 6204258970
13 49675571820
14 402013608525
15 3284214703056
16 27055525967324
17 224557688302164
18 1876374953765620
19 15774315150669075
20 133345566025874055