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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 9 |
| 8 | 16 |
| 9 | 38 |
| 10 | 104 |
| 11 | 267 |
| 12 | 608 |
| 13 | 1444 |
| 14 | 3480 |
| 15 | 8221 |
| 16 | 19212 |
| 17 | 45262 |
| 18 | 213280 |
| 19 | 250247 |
| 20 | 587072 |
| 21 | 1378912 |
| 22 | 3237456 |
[0,0,0,0,0,0,9,16,38,104,267,608,1444,3480,8221, 19212,45262,213280,250247,587072,1378912,3237456] |