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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 16 |
| 3 | 106 |
| 4 | 786 |
| 5 | 6244 |
| 6 | 51964 |
| 7 | 447201 |
| 8 | 3947306 |
| 9 | 35538668 |
| 10 | 325098696 |
| 11 | 3013060258 |
| 12 | 28232408848 |
| 13 | 267003169668 |
| 14 | 2545341982728 |
| 15 | 24433290332007 |
| 16 | 235967943943224 |
| 17 | 2291147902820524 |
| 18 | 22352525061549604 |
| 19 | 219006814853751540 |
| 20 | 2154083325737401740 |
[1,3,16,106,786,6244,51964,447201,3947306, 35538668,325098696,3013060258,28232408848, 267003169668,2545341982728,24433290332007, 235967943943224,2291147902820524, 22352525061549604,219006814853751540, 2154083325737401740] |