| n | a(n) |
|---|---|
| 6 | 1 |
| 7 | 4 |
| 8 | 16 |
| 9 | 53 |
| 10 | 175 |
| 11 | 547 |
| 12 | 1692 |
| 13 | 5127 |
| 14 | 15408 |
| 15 | 45831 |
| 16 | 135500 |
| 17 | 398186 |
| 18 | 1165005 |
| 19 | 3394880 |
| 20 | 9861048 |
| 21 | 28561403 |
| 22 | 82525483 |
| 23 | 237941827 |
| 24 | 684778523 |
| 25 | 1967510639 |
[1,4,16,53,175,547,1692,5127,15408,45831,135500, 398186,1165005,3394880,9861048,28561403,82525483, 237941827,684778523,1967510639] |