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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 1 |
| 7 | 2 |
| 8 | 9 |
| 9 | 35 |
| 10 | 177 |
| 11 | 1153 |
| 12 | 10341 |
| 13 | 120523 |
| 14 | 1702432 |
| 15 | 27507351 |
| 16 | 492377298 |
| 17 | 9600913017 |
| 18 | 201990426697 |
| 19 | 4555849947783 |
[0,0,0,0,0,0,1,2,9,35,177,1153,10341,120523, 1702432,27507351,492377298,9600913017, 201990426697,4555849947783] |