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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 0 |
| 8 | 0 |
| 9 | 1 |
| 10 | 6 |
| 11 | 21 |
| 12 | 68 |
| 13 | 199 |
| 14 | 545 |
| 15 | 1410 |
| 16 | 3530 |
| 17 | 8557 |
| 18 | 20255 |
| 19 | 46968 |
| 20 | 107135 |
| 21 | 240927 |
| 22 | 535379 |
| 23 | 1177435 |
| 24 | 2566618 |
| 25 | 5551456 |
[0,0,0,0,0,0,0,0,0,1,6,21,68,199,545,1410,3530, 8557,20255,46968,107135,240927,535379,1177435, 2566618,5551456] |