The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 9 |
| 3 | 54 |
| 4 | 321 |
| 5 | 1821 |
| 6 | 9919 |
| 7 | 52532 |
| 8 | 272997 |
| 9 | 1401993 |
| 10 | 7150718 |
| 11 | 36352875 |
| 12 | 184670276 |
| 13 | 938969921 |
| 14 | 4783571827 |
| 15 | 24431153268 |
| 16 | 125119394092 |
[2,9,54,321,1821,9919,52532,272997,1401993, 7150718,36352875,184670276,938969921,4783571827, 24431153268,125119394092] |