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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 3 |
| 4 | 6 |
| 5 | 10 |
| 6 | 195 |
| 7 | 1281 |
| 8 | 5908 |
| 9 | 90756 |
| 10 | 1098765 |
| 11 | 9605035 |
| 12 | 147947646 |
| 13 | 2496239538 |
| 14 | 33836915203 |
| 15 | 588360763095 |
| 16 | 12104789358600 |
| 17 | 223722576473896 |
| 18 | 4578806487368313 |
| 19 | 108875473376842467 |
| 20 | 2519418390663035170 |
| 21 | 60831875074927797750 |
| 22 | 1640260621340460494991 |
[0,0,0,3,6,10,195,1281,5908,90756,1098765,9605035, 147947646,2496239538,33836915203,588360763095, 12104789358600,223722576473896,4578806487368313, 108875473376842467,2519418390663035170, 60831875074927797750,1640260621340460494991] |