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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 6 |
| 4 | 17 |
| 5 | 40 |
| 6 | 217 |
| 7 | 1358 |
| 8 | 6449 |
| 9 | 29712 |
| 10 | 182049 |
| 11 | 1270390 |
| 12 | 8227617 |
| 13 | 52843960 |
| 14 | 383647513 |
| 15 | 3038764542 |
| 16 | 23995450017 |
| 17 | 191131924256 |
| 18 | 1621685573121 |
| 19 | 14574192364646 |
| 20 | 133472613190001 |
| 21 | 1244028051397192 |
| 22 | 12068806481240601 |
[1,0,1,6,17,40,217,1358,6449,29712,182049,1270390, 8227617,52843960,383647513,3038764542,23995450017, 191131924256,1621685573121,14574192364646, 133472613190001,1244028051397192, 12068806481240601] |