# A083693 (b-file synthesized from sequence entry)
0 1
1 4
2 18
3 72
4 324
5 1360
6 6280
7 27296
8 128784
9 573760
10 2752032
11 12485248
12 60652608
13 278988032
14 1368979584
15 6365514240
16 31488733440
17 147697177600
18 735486927360
19 3474529986560
20 17398140748800
21 82683153633280
22 415966710171648