| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 7 |
| 5 | 5 |
| 6 | 40 |
| 7 | 19 |
| 8 | 418 |
| 9 | 491 |
| 10 | 27240 |
| 11 | 24451 |
| 12 | 2971576 |
| 13 | 2078908 |
| 14 | 614382155 |
| 15 | 474528877 |
| 16 | 322682051335 |
| 17 | 262749927910 |
| 18 | 400764203886592 |
| 19 | 313224621598547 |
| 20 | 1137774558755597994 |
| 21 | 881352408772896894 |
| 22 | 7433275932107389413579 |
[1,1,1,7,5,40,19,418,491,27240,24451,2971576, 2078908,614382155,474528877,322682051335, 262749927910,400764203886592,313224621598547, 1137774558755597994,881352408772896894, 7433275932107389413579] |