The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 9 |
| 6 | 13 |
| 7 | 45 |
| 8 | 103 |
| 9 | 3361 |
| 10 | 8833 |
| 11 | 372663 |
| 12 | 1287127 |
| 13 | 106100985 |
| 14 | 471171193 |
| 15 | 109709730093 |
| 16 | 638573372655 |
| 17 | 304442910936313 |
| 18 | 2309148561615411 |
| 19 | 2461266528050264151 |
| 20 | 24325578567487185537 |
| 21 | 57639766702959393452219 |
[1,1,1,1,9,13,45,103,3361,8833,372663,1287127, 106100985,471171193,109709730093,638573372655, 304442910936313,2309148561615411, 2461266528050264151,24325578567487185537, 57639766702959393452219] |