| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 1 |
| 6 | 1 |
| 7 | 1 |
| 8 | 5 |
| 9 | 25 |
| 10 | 49 |
| 11 | 81 |
| 12 | 173 |
| 13 | 659 |
| 14 | 1949 |
| 15 | 6591 |
| 16 | 26979 |
| 17 | 151047 |
| 18 | 720521 |
| 19 | 4123761 |
| 20 | 21126009 |
| 21 | 143739573 |
[1,1,1,1,1,1,1,5,25,49,81,173,659,1949,6591,26979, 151047,720521,4123761,21126009,143739573] |