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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 2 |
| 4 | 5 |
| 5 | 12 |
| 6 | 32 |
| 7 | 88 |
| 8 | 260 |
| 9 | 819 |
| 10 | 2680 |
| 11 | 8642 |
| 12 | 27976 |
| 13 | 88946 |
| 14 | 281541 |
| 15 | 893028 |
| 16 | 2841344 |
| 17 | 9092174 |
| 18 | 29176634 |
| 19 | 93854841 |
| 20 | 302611365 |
[1,2,5,12,32,88,260,819,2680,8642,27976,88946, 281541,893028,2841344,9092174,29176634,93854841, 302611365] |