| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 7 |
| 6 | 14 |
| 7 | 20 |
| 8 | 39 |
| 9 | 102 |
| 10 | 156 |
| 11 | 457 |
| 12 | 1190 |
| 13 | 2308 |
| 14 | 5870 |
| 15 | 8314 |
| 16 | 9703 |
| 17 | 12828 |
| 18 | 14959 |
| 19 | 17995 |
| 20 | 19730 |
| 21 | 26480 |
| 22 | 31440 |
[0,1,2,4,7,14,20,39,102,156,457,1190,2308,5870, 8314,9703,12828,14959,17995,19730,26480,31440] |