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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 12 |
| 5 | 20 |
| 6 | 35 |
| 7 | 56 |
| 8 | 92 |
| 9 | 142 |
| 10 | 221 |
| 11 | 330 |
| 12 | 496 |
| 13 | 724 |
| 14 | 1056 |
| 15 | 1512 |
| 16 | 2155 |
| 17 | 3028 |
| 18 | 4240 |
| 19 | 5866 |
| 20 | 8085 |
[1,1,3,6,12,20,35,56,92,142,221,330,496,724,1056, 1512,2155,3028,4240,5866,8085] |