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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 6 |
| 3 | 13 |
| 4 | 25 |
| 5 | 55 |
| 6 | 100 |
| 7 | 222 |
| 8 | 401 |
| 9 | 891 |
| 10 | 1602 |
| 11 | 3559 |
| 12 | 6428 |
| 13 | 14258 |
| 14 | 25647 |
| 15 | 56936 |
| 16 | 102860 |
| 17 | 228154 |
| 18 | 410339 |
| 19 | 910998 |
| 20 | 1645813 |
| 21 | 3650437 |
| 22 | 6565453 |
| 23 | 14576121 |
| 24 | 26332935 |
| 25 | 58407052 |
| 26 | 105047514 |
| 27 | 233217299 |
| 28 | 421327294 |
| 29 | 934513441 |
| 30 | 1680759539 |
[1,3,6,13,25,55,100,222,401,891,1602,3559,6428, 14258,25647,56936,102860,228154,410339,910998, 1645813,3650437,6565453,14576121,26332935, 58407052,105047514,233217299,421327294,934513441, 1680759539] |