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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 0 |
| 5 | 3 |
| 6 | 6 |
| 7 | 0 |
| 8 | 53 |
| 9 | 199 |
| 10 | 0 |
| 11 | 2908 |
| 12 | 13699 |
| 13 | 0 |
| 14 | 369985 |
| 15 | 2135430 |
| 16 | 0 |
| 17 | 87265700 |
| 18 | 611286653 |
| 19 | 0 |
| 20 | 34928617573 |
| 21 | 284205647124 |
| 22 | 0 |
[1,0,1,1,0,3,6,0,53,199,0,2908,13699,0,369985, 2135430,0,87265700,611286653,0,34928617573, 284205647124,0] |