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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 25 |
| 4 | 350 |
| 5 | 6951 |
| 6 | 179487 |
| 7 | 5715424 |
| 8 | 216627840 |
| 9 | 9528822303 |
| 10 | 477297033785 |
| 11 | 26826851689001 |
| 12 | 1672162773483930 |
| 13 | 114485073343744260 |
| 14 | 8541149231801585700 |
| 15 | 689692892575539953400 |
| 16 | 59932861644880019603520 |
| 17 | 5576731051262006158950735 |
| 18 | 553234633385550257808059085 |
[1,3,25,350,6951,179487,5715424,216627840, 9528822303,477297033785,26826851689001, 1672162773483930,114485073343744260, 8541149231801585700,689692892575539953400, 59932861644880019603520,5576731051262006158950735, 553234633385550257808059085] |