# A081947 (b-file synthesized from sequence entry)
1 2
2 3
3 7
4 31
5 181
6 1009
7 6481
8 45361
9 453601
10 3991681
11 39916801
12 566092801
13 9500198401
14 114960384001
15 1976041267201
16 24845812992001
17 502146957312001
18 8109673360588801
19 147254595231744001
20 2688996956405760001