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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 6 |
| 6 | 19 |
| 7 | 20 |
| 8 | 111 |
| 9 | 116 |
| 10 | 567 |
| 11 | 641 |
| 12 | 4718 |
| 13 | 4772 |
| 14 | 35489 |
| 15 | 46012 |
| 16 | 389277 |
| 17 | 487408 |
| 18 | 4616580 |
[0,1,1,2,4,6,19,20,111,116,567,641,4718,4772, 35489,46012,389277,487408,4616580] |