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 | 4 |
| 6 | 2 |
| 7 | 1 |
| 8 | 15 |
| 9 | 12 |
| 10 | 3 |
| 11 | 1 |
| 12 | 54 |
| 13 | 105 |
| 14 | 39 |
| 15 | 6 |
| 16 | 1 |
| 17 | 221 |
| 18 | 863 |
| 19 | 566 |
| 20 | 117 |
| 21 | 11 |
[1,1,1,1,4,2,1,15,12,3,1,54,105,39,6,1,221,863, 566,117,11] |