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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 49 |
| 5 | 409 |
| 6 | 4356 |
| 7 | 56734 |
| 8 | 877094 |
| 9 | 15742521 |
| 10 | 322454800 |
| 11 | 7434673036 |
| 12 | 190792267128 |
| 13 | 5398552673617 |
| 14 | 167087263076384 |
| 15 | 5617979017621650 |
| 16 | 203987454978218416 |
| 17 | 7957053981454827601 |
| 18 | 331920300203780633856 |
| 19 | 14746208516909980554736 |
| 20 | 695208730205550274544000 |
[1,2,8,49,409,4356,56734,877094,15742521, 322454800,7434673036,190792267128,5398552673617, 167087263076384,5617979017621650, 203987454978218416,7957053981454827601, 331920300203780633856,14746208516909980554736, 695208730205550274544000] |