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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 28 |
| 3 | 252 |
| 4 | 2270 |
| 5 | 20433 |
| 6 | 183898 |
| 7 | 1655082 |
| 8 | 14895740 |
| 9 | 134061663 |
| 10 | 1206554968 |
| 11 | 10858994712 |
| 12 | 97730952410 |
| 13 | 879578571693 |
| 14 | 7916207145238 |
| 15 | 71245864307142 |
| 16 | 641212778764280 |
| 17 | 5770915008878523 |
[3,28,252,2270,20433,183898,1655082,14895740, 134061663,1206554968,10858994712,97730952410, 879578571693,7916207145238,71245864307142, 641212778764280,5770915008878523] |