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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 11 |
| 4 | 88 |
| 5 | 638 |
| 6 | 4466 |
| 7 | 30856 |
| 8 | 212135 |
| 9 | 1455685 |
| 10 | 9981840 |
| 11 | 68428140 |
| 12 | 469043796 |
| 13 | 3214953456 |
| 14 | 22035826813 |
| 15 | 151036348463 |
| 16 | 1035219958696 |
| 17 | 7095506886986 |
| 18 | 48633337477670 |
| 19 | 333337879614520 |
| 20 | 2284731883069955 |
| 21 | 15659785467455305 |
[0,0,1,11,88,638,4466,30856,212135,1455685, 9981840,68428140,469043796,3214953456,22035826813, 151036348463,1035219958696,7095506886986, 48633337477670,333337879614520,2284731883069955, 15659785467455305] |