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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 20 |
| 4 | 23 |
| 5 | 1655 |
| 6 | 39597 |
| 7 | 336788 |
| 8 | 2130707 |
| 9 | 97253704 |
| 10 | 2328983293 |
| 11 | 27777628803 |
| 12 | 109663812046 |
| 13 | 7330508486557 |
| 14 | 181851333483598 |
| 15 | 2032109646360324 |
| 16 | 8979878533633165 |
| 17 | 588003317861300327 |
[0,0,20,23,1655,39597,336788,2130707,97253704, 2328983293,27777628803,109663812046,7330508486557, 181851333483598,2032109646360324,8979878533633165, 588003317861300327] |