The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 22 |
| 5 | 138 |
| 6 | 930 |
| 7 | 6561 |
| 8 | 47800 |
| 9 | 356728 |
| 10 | 2712758 |
| 11 | 20944303 |
| 12 | 163738947 |
| 13 | 1293610671 |
| 14 | 10312170488 |
| 15 | 82843804507 |
| 16 | 670045658032 |
| 17 | 5451693184584 |
| 18 | 44591169828366 |
| 19 | 366447128131373 |
| 20 | 3024200357007623 |
| 21 | 25053501077514721 |
| 22 | 208272200149758543 |
| 23 | 1736864093227610857 |
[0,1,1,4,22,138,930,6561,47800,356728,2712758, 20944303,163738947,1293610671,10312170488, 82843804507,670045658032,5451693184584, 44591169828366,366447128131373,3024200357007623, 25053501077514721,208272200149758543, 1736864093227610857] |