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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 23 |
| 2 | 506 |
| 3 | 11132 |
| 4 | 244904 |
| 5 | 5387888 |
| 6 | 118533536 |
| 7 | 2607737792 |
| 8 | 57370231424 |
| 9 | 1262145091328 |
| 10 | 27767192009216 |
| 11 | 610878224202752 |
| 12 | 13439320932460544 |
| 13 | 295665060514131968 |
| 14 | 6504631331310903296 |
| 15 | 143101889288839872512 |
[1,23,506,11132,244904,5387888,118533536, 2607737792,57370231424,1262145091328, 27767192009216,610878224202752,13439320932460544, 295665060514131968,6504631331310903296, 143101889288839872512] |