| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 14 |
| 4 | 85 |
| 5 | 632 |
| 6 | 5559 |
| 7 | 56352 |
| 8 | 645929 |
| 9 | 8252352 |
| 10 | 116189291 |
| 11 | 1786361216 |
| 12 | 29764770941 |
| 13 | 534082233856 |
| 14 | 10264484355103 |
| 15 | 210312181051392 |
| 16 | 4575364233983057 |
| 17 | 105310034714202112 |
| 18 | 2556360647841415379 |
| 19 | 65261358332774277120 |
| 20 | 1747713179543456515749 |
[1,1,3,14,85,632,5559,56352,645929,8252352, 116189291,1786361216,29764770941,534082233856, 10264484355103,210312181051392,4575364233983057, 105310034714202112,2556360647841415379, 65261358332774277120,1747713179543456515749] |