# A113990 (b-file synthesized from sequence entry)
0 1
1 4
2 12
3 36
4 116
5 416
6 1680
7 7656
8 39256
9 225348
10 1439868
11 10179116
12 79153484
13 673262240
14 6231517920
15 62461031920
16 675005395152
17 7832909636740
18 97238472215564
19 1286967352638292
20 18102901048062404
21 269852768731391808