| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 3 |
| 5 | 10 |
| 6 | 28 |
| 7 | 164 |
| 8 | 905 |
| 9 | 9826 |
| 10 | 103126 |
| 11 | 2031252 |
| 12 | 43437282 |
| 13 | 1622278624 |
| 14 | 66141208960 |
| 15 | 4579408029576 |
| 16 | 385335180349569 |
| 17 | 51207103076632066 |
| 18 | 8212830157184175946 |
| 19 | 2052124795850957537060 |
| 20 | 683805150345009276656138 |
[1,1,2,3,10,28,164,905,9826,103126,2031252, 43437282,1622278624,66141208960,4579408029576, 385335180349569,51207103076632066, 8212830157184175946,2052124795850957537060, 683805150345009276656138] |