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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 3 |
| 3 | 18 |
| 4 | 189 |
| 5 | 2484 |
| 6 | 40095 |
| 7 | 766422 |
| 8 | 16936857 |
| 9 | 424878696 |
| 10 | 11929019931 |
| 11 | 370616958810 |
| 12 | 12624017298453 |
| 13 | 467806833261468 |
| 14 | 18736803171836919 |
| 15 | 806593620214132254 |
| 16 | 37139869052368612785 |
| 17 | 1821430208283971761872 |
| 18 | 94787073944153359107507 |
| 19 | 5216859224231615866946466 |
[1,0,3,18,189,2484,40095,766422,16936857, 424878696,11929019931,370616958810,12624017298453, 467806833261468,18736803171836919, 806593620214132254,37139869052368612785, 1821430208283971761872,94787073944153359107507, 5216859224231615866946466] |