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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 12 |
| 5 | 72 |
| 6 | 467 |
| 7 | 2900 |
| 8 | 18426 |
| 9 | 117323 |
| 10 | 756237 |
| 11 | 4910525 |
| 12 | 32135651 |
| 13 | 211604221 |
| 14 | 1401106330 |
| 15 | 9321239836 |
| 16 | 62271754986 |
| 17 | 417545272654 |
[0,0,1,12,72,467,2900,18426,117323,756237,4910525, 32135651,211604221,1401106330,9321239836, 62271754986,417545272654] |