| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 7 |
| 3 | 20 |
| 4 | 41 |
| 5 | 178 |
| 6 | 388 |
| 7 | 628 |
| 8 | 1708 |
| 9 | 2860 |
| 10 | 4002 |
| 11 | 9979 |
| 12 | 17394 |
| 13 | 15401 |
| 14 | 63332 |
| 15 | 135334 |
| 16 | 82102 |
| 17 | 702695 |
| 18 | 2582167 |
| 19 | 1191816 |
| 20 | 17532272 |
| 21 | 141444005 |
| 22 | 38062610 |
[1,7,20,41,178,388,628,1708,2860,4002,9979,17394, 15401,63332,135334,82102,702695,2582167,1191816, 17532272,141444005,38062610] |