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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 18 |
| 4 | 227 |
| 5 | 12125 |
| 6 | 542448 |
| 7 | 55071205 |
| 8 | 5492843269 |
| 9 | 905996551626 |
| 10 | 159770279801855 |
| 11 | 39299019878991521 |
| 12 | 10721872262093222016 |
| 13 | 3707660329253983397113 |
| 14 | 1438816154956071399594457 |
| 15 | 668949924061617421125859650 |
| 16 | 348908555505788456739965412203 |
[0,1,1,18,227,12125,542448,55071205,5492843269, 905996551626,159770279801855,39299019878991521, 10721872262093222016,3707660329253983397113, 1438816154956071399594457, 668949924061617421125859650, 348908555505788456739965412203] |