| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 15 |
| 5 | 81 |
| 6 | 237 |
| 7 | 1015 |
| 8 | 3891 |
| 9 | 16171 |
| 10 | 66237 |
| 11 | 297003 |
| 12 | 1304467 |
| 13 | 5981617 |
| 14 | 27407859 |
| 15 | 126441771 |
| 16 | 584452845 |
| 17 | 2721978059 |
| 18 | 12719931479 |
| 19 | 59862174023 |
| 20 | 282898499059 |
| 21 | 1341705275365 |
| 22 | 6380905008633 |
| 23 | 30422523202843 |
| 24 | 145340620435425 |
[1,1,5,15,81,237,1015,3891,16171,66237,297003, 1304467,5981617,27407859,126441771,584452845, 2721978059,12719931479,59862174023,282898499059, 1341705275365,6380905008633,30422523202843, 145340620435425] |