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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 6 |
| 4 | 75 |
| 5 | 1338 |
| 6 | 29610 |
| 7 | 762228 |
| 8 | 22038705 |
| 9 | 700625130 |
| 10 | 24149689410 |
| 11 | 893830956468 |
| 12 | 35275412216850 |
| 13 | 1476645034008396 |
| 14 | 65297205101393700 |
| 15 | 3040249608438530040 |
| 16 | 148645372286538383895 |
| 17 | 7614315445406159805786 |
| 18 | 407837347813468711863270 |
[1,1,6,75,1338,29610,762228,22038705,700625130, 24149689410,893830956468,35275412216850, 1476645034008396,65297205101393700, 3040249608438530040,148645372286538383895, 7614315445406159805786,407837347813468711863270] |