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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 3 |
| 5 | 18 |
| 6 | 110 |
| 7 | 795 |
| 8 | 6489 |
| 9 | 59332 |
| 10 | 600732 |
| 11 | 6674805 |
| 12 | 80765135 |
| 13 | 1057289046 |
| 14 | 14890154058 |
| 15 | 224497707343 |
| 16 | 3607998868005 |
| 17 | 61576514013960 |
| 18 | 1112225784377144 |
| 19 | 21197714949305577 |
| 20 | 425131949816628507 |
| 21 | 8950146311929021210 |
| 22 | 197350726178034917670 |
| 23 | 4548464355722328578691 |
[0,0,1,3,18,110,795,6489,59332,600732,6674805, 80765135,1057289046,14890154058,224497707343, 3607998868005,61576514013960,1112225784377144, 21197714949305577,425131949816628507, 8950146311929021210,197350726178034917670, 4548464355722328578691] |