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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 22 |
| 2 | 355 |
| 3 | 5265 |
| 4 | 77224 |
| 5 | 1155420 |
| 6 | 17893196 |
| 7 | 288843260 |
| 8 | 4876196776 |
| 9 | 86194186584 |
| 10 | 1595481972864 |
| 11 | 30908820004608 |
| 12 | 626110382381184 |
| 13 | 13246845128678016 |
| 14 | 292374329134060800 |
| 15 | 6723367631258860800 |
| 16 | 160883166944083161600 |
| 17 | 4001062259532015244800 |
[1,22,355,5265,77224,1155420,17893196,288843260, 4876196776,86194186584,1595481972864, 30908820004608,626110382381184,13246845128678016, 292374329134060800,6723367631258860800, 160883166944083161600,4001062259532015244800] |