The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 81 |
| 2 | 558 |
| 3 | 3844 |
| 4 | 26784 |
| 5 | 186624 |
| 6 | 1296000 |
| 7 | 9000000 |
| 8 | 62568000 |
| 9 | 434972736 |
| 10 | 3022785216 |
| 11 | 21006444096 |
| 12 | 146001569472 |
| 13 | 1014758051904 |
| 14 | 7052535822528 |
| 15 | 49014897132096 |
| 16 | 340658500222656 |
| 17 | 2367611084874816 |
| 18 | 16455017381102784 |
| 19 | 114363207176279616 |
[81,558,3844,26784,186624,1296000,9000000, 62568000,434972736,3022785216,21006444096, 146001569472,1014758051904,7052535822528, 49014897132096,340658500222656,2367611084874816, 16455017381102784,114363207176279616] |