The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 81 |
| 2 | 459 |
| 3 | 1963 |
| 4 | 7253 |
| 5 | 25165 |
| 6 | 85663 |
| 7 | 291511 |
| 8 | 997121 |
| 9 | 3427953 |
| 10 | 11826315 |
| 11 | 40885971 |
| 12 | 141512469 |
| 13 | 490082653 |
| 14 | 1697732055 |
| 15 | 5882051383 |
| 16 | 20380576545 |
| 17 | 70618256025 |
| 18 | 244694019755 |
| 19 | 847876017411 |
| 20 | 2937937280013 |
| 21 | 10180127318973 |
| 22 | 35274764991959 |
[81,459,1963,7253,25165,85663,291511,997121, 3427953,11826315,40885971,141512469,490082653, 1697732055,5882051383,20380576545,70618256025, 244694019755,847876017411,2937937280013, 10180127318973,35274764991959] |