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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 4536 |
| 5 | 45360 |
| 6 | 294840 |
| 7 | 1587600 |
| 8 | 7715736 |
| 9 | 35244720 |
| 10 | 154700280 |
| 11 | 661122000 |
| 12 | 2773768536 |
| 13 | 11487556080 |
| 14 | 47136955320 |
| 15 | 192126589200 |
| 16 | 779279814936 |
| 17 | 3149513947440 |
| 18 | 12695388483960 |
| 19 | 51073849285200 |
| 20 | 205172877726936 |
| 21 | 823325141746800 |
| 22 | 3301203837670200 |
| 23 | 13228529919066000 |
[0,0,0,4536,45360,294840,1587600,7715736,35244720, 154700280,661122000,2773768536,11487556080, 47136955320,192126589200,779279814936, 3149513947440,12695388483960,51073849285200, 205172877726936,823325141746800,3301203837670200, 13228529919066000] |