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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 5 |
| 3 | 34 |
| 4 | 144 |
| 5 | 490 |
| 6 | 1470 |
| 7 | 3990 |
| 8 | 10045 |
| 9 | 23750 |
| 10 | 53205 |
| 11 | 113694 |
| 12 | 233039 |
| 13 | 460096 |
| 14 | 878269 |
| 15 | 1626034 |
[0,5,34,144,490,1470,3990,10045,23750,53205, 113694,233039,460096,878269,1626034] |