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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 520 |
| 5 | 5632 |
| 6 | 31176 |
| 7 | 135240 |
| 8 | 429360 |
| 9 | 1211208 |
| 10 | 3028224 |
| 11 | 6888216 |
| 12 | 13961448 |
| 13 | 28262776 |
| 14 | 52206088 |
| 15 | 91745904 |
| 16 | 157574640 |
| 17 | 263360352 |
| 18 | 418048464 |
| 19 | 657072528 |
| 20 | 991543416 |
| 21 | 1487807520 |
| 22 | 2194825240 |
| 23 | 3156000184 |
| 24 | 4416200736 |
| 25 | 6212710248 |
[0,0,0,520,5632,31176,135240,429360,1211208, 3028224,6888216,13961448,28262776,52206088, 91745904,157574640,263360352,418048464,657072528, 991543416,1487807520,2194825240,3156000184, 4416200736,6212710248] |