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| n | a(n) |
|---|---|
| 1 | 15 |
| 2 | 225 |
| 3 | 2321 |
| 4 | 19608 |
| 5 | 160362 |
| 6 | 1351748 |
| 7 | 11704964 |
| 8 | 102319662 |
| 9 | 895494806 |
| 10 | 7833508842 |
| 11 | 68530349850 |
| 12 | 599768316699 |
| 13 | 5250822841015 |
| 14 | 45977188883801 |
| 15 | 402610713736831 |
| 16 | 3525653178203557 |
| 17 | 30874547729660838 |
| 18 | 270374890703092436 |
[15,225,2321,19608,160362,1351748,11704964, 102319662,895494806,7833508842,68530349850, 599768316699,5250822841015,45977188883801, 402610713736831,3525653178203557, 30874547729660838,270374890703092436] |