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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 34 |
| 4 | 416 |
| 5 | 6319 |
| 6 | 111124 |
| 7 | 2177346 |
| 8 | 46440184 |
| 9 | 1061938195 |
| 10 | 25762345804 |
| 11 | 658072997702 |
| 12 | 17600573291712 |
| 13 | 490770914734054 |
| 14 | 14219015899154068 |
| 15 | 426904437068035200 |
| 16 | 13252855203929697200 |
| 17 | 424634035832800883743 |
| 18 | 14020984603588221319072 |
| 19 | 476460483567807053745450 |
[1,1,4,34,416,6319,111124,2177346,46440184, 1061938195,25762345804,658072997702, 17600573291712,490770914734054,14219015899154068, 426904437068035200,13252855203929697200, 424634035832800883743,14020984603588221319072, 476460483567807053745450] |