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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 6 |
| 5 | 16 |
| 6 | 39 |
| 7 | 103 |
| 8 | 263 |
| 9 | 690 |
| 10 | 1791 |
| 11 | 4693 |
| 12 | 12247 |
| 13 | 32073 |
| 14 | 83869 |
| 15 | 219598 |
| 16 | 574658 |
| 17 | 1504540 |
| 18 | 3938272 |
| 19 | 10310703 |
[1,1,3,6,16,39,103,263,690,1791,4693,12247,32073, 83869,219598,574658,1504540,3938272,10310703] |