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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 15 |
| 4 | 198 |
| 5 | 2282 |
| 6 | 19300 |
| 7 | 126861 |
| 8 | 670058 |
| 9 | 2997685 |
| 10 | 11539243 |
| 11 | 39660969 |
| 12 | 122371876 |
| 13 | 348412793 |
| 14 | 914595808 |
| 15 | 2264326584 |
| 16 | 5259342780 |
| 17 | 11692554312 |
| 18 | 24683815072 |
| 19 | 50403390786 |
| 20 | 98560661538 |
| 21 | 187881799209 |
| 22 | 345060981679 |
| 23 | 621482071341 |
[0,1,15,198,2282,19300,126861,670058,2997685, 11539243,39660969,122371876,348412793,914595808, 2264326584,5259342780,11692554312,24683815072, 50403390786,98560661538,187881799209,345060981679, 621482071341] |