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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 10 |
| 4 | 51 |
| 5 | 312 |
| 6 | 2285 |
| 7 | 19776 |
| 8 | 193641 |
| 9 | 2143872 |
| 10 | 26332083 |
| 11 | 355752000 |
| 12 | 5245533579 |
| 13 | 83760362496 |
| 14 | 1440626560893 |
| 15 | 26546198746368 |
| 16 | 521773563403665 |
| 17 | 10896758207668224 |
| 18 | 240952051977165603 |
| 19 | 5624033606823011328 |
| 20 | 138178553037552463779 |
| 21 | 3564697656160155156480 |
| 22 | 96340383688983485779917 |
[1,1,3,10,51,312,2285,19776,193641,2143872, 26332083,355752000,5245533579,83760362496, 1440626560893,26546198746368,521773563403665, 10896758207668224,240952051977165603, 5624033606823011328,138178553037552463779, 3564697656160155156480,96340383688983485779917] |