| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 8 |
| 6 | 37 |
| 7 | 229 |
| 8 | 1648 |
| 9 | 13508 |
| 10 | 124269 |
| 11 | 1267543 |
| 12 | 14196478 |
| 13 | 173197025 |
| 14 | 2286200719 |
| 15 | 32464050200 |
| 16 | 493453563030 |
| 17 | 7993947721072 |
| 18 | 137495900802424 |
| 19 | 2502425394604114 |
| 20 | 48046567576398987 |
| 21 | 970540665043259526 |
[1,1,1,1,2,8,37,229,1648,13508,124269,1267543, 14196478,173197025,2286200719,32464050200, 493453563030,7993947721072,137495900802424, 2502425394604114,48046567576398987, 970540665043259526] |