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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 2 |
| 2 | 0 |
| 3 | 1 |
| 4 | 6 |
| 5 | 17 |
| 6 | 60 |
| 7 | 271 |
| 8 | 1386 |
| 9 | 7937 |
| 10 | 50520 |
| 11 | 353791 |
| 12 | 2702766 |
| 13 | 22368257 |
| 14 | 199360980 |
| 15 | 1903757311 |
| 16 | 19391512146 |
| 17 | 209865342977 |
| 18 | 2404879675440 |
| 19 | 29088885112831 |
| 20 | 370371188237526 |
| 21 | 4951498053124097 |
| 22 | 69348874393137900 |
| 23 | 1015423886506852351 |
| 24 | 15514534163557086906 |
[2,2,0,1,6,17,60,271,1386,7937,50520,353791, 2702766,22368257,199360980,1903757311,19391512146, 209865342977,2404879675440,29088885112831, 370371188237526,4951498053124097, 69348874393137900,1015423886506852351, 15514534163557086906] |