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| n | a(n) |
|---|---|
| 2 | 0 |
| 3 | 3 |
| 4 | 28 |
| 5 | 210 |
| 6 | 1506 |
| 7 | 10871 |
| 8 | 80592 |
| 9 | 618939 |
| 10 | 4942070 |
| 11 | 41076508 |
| 12 | 355372524 |
| 13 | 3198027157 |
| 14 | 29905143464 |
| 15 | 290243182755 |
| 16 | 2920041395248 |
| 17 | 30414515081650 |
| 18 | 327567816748638 |
| 19 | 3643600859114439 |
| 20 | 41809197852127240 |
| 21 | 494367554679088923 |
| 22 | 6017481714095327410 |
[0,3,28,210,1506,10871,80592,618939,4942070, 41076508,355372524,3198027157,29905143464, 290243182755,2920041395248,30414515081650, 327567816748638,3643600859114439, 41809197852127240,494367554679088923, 6017481714095327410] |