# A013320 (b-file synthesized from sequence entry)
0 1
1 0
2 1
3 6
4 21
5 120
6 1077
7 8918
8 83097
9 952560
10 11790649
11 156839430
12 2318954253
13 37207496040
14 637980683277
15 11745733936022
16 231142374081009
17 4825295491430880
18 106636356923768497
19 2489165244414184326