| n | a(n) |
|---|---|
| 1 | 81 |
| 2 | 328 |
| 3 | 1342 |
| 4 | 5622 |
| 5 | 23545 |
| 6 | 97700 |
| 7 | 406008 |
| 8 | 1690160 |
| 9 | 7044600 |
| 10 | 29290848 |
| 11 | 121938192 |
| 12 | 507239832 |
| 13 | 2112696916 |
| 14 | 8786861808 |
| 15 | 36590339088 |
| 16 | 152192510432 |
| 17 | 633818640688 |
| 18 | 2636209092480 |
| 19 | 10978287344480 |
| 20 | 45661928555744 |
| 21 | 190158818087504 |
[81,328,1342,5622,23545,97700,406008,1690160, 7044600,29290848,121938192,507239832,2112696916, 8786861808,36590339088,152192510432,633818640688, 2636209092480,10978287344480,45661928555744, 190158818087504] |