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| n | a(n) |
|---|---|
| 0 | 15 |
| 1 | 210 |
| 2 | 1750 |
| 3 | 11368 |
| 4 | 63805 |
| 5 | 325930 |
| 6 | 1561516 |
| 7 | 7150000 |
| 8 | 31682651 |
| 9 | 137031986 |
| 10 | 582035714 |
| 11 | 2438479592 |
| 12 | 10109790809 |
| 13 | 41579014154 |
| 14 | 169946747160 |
| 15 | 691299506640 |
| 16 | 2801567046135 |
| 17 | 11320801495410 |
| 18 | 45642930545070 |
| 19 | 183698923750440 |
[15,210,1750,11368,63805,325930,1561516,7150000, 31682651,137031986,582035714,2438479592, 10109790809,41579014154,169946747160,691299506640, 2801567046135,11320801495410,45642930545070, 183698923750440] |