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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 1 |
| 6 | 1 |
| 7 | 2 |
| 8 | 3 |
| 9 | 6 |
| 10 | 9 |
| 11 | 16 |
| 12 | 23 |
| 13 | 72 |
| 14 | 177 |
| 15 | 631 |
| 16 | 1684 |
| 17 | 5696 |
| 18 | 15819 |
| 19 | 69884 |
| 20 | 263612 |
| 21 | 1492069 |
| 22 | 6667995 |
| 23 | 40872228 |
| 24 | 203062570 |
| 25 | 1480955534 |
| 26 | 9070964673 |
| 27 | 81908729534 |
[1,1,1,1,1,1,2,3,6,9,16,23,72,177,631,1684,5696, 15819,69884,263612,1492069,6667995,40872228, 203062570,1480955534,9070964673,81908729534] |