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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 2 |
| 5 | 4 |
| 6 | 9 |
| 7 | 15 |
| 8 | 30 |
| 9 | 54 |
| 10 | 101 |
| 11 | 181 |
| 12 | 344 |
| 13 | 624 |
| 14 | 1173 |
| 15 | 2183 |
| 16 | 4106 |
| 17 | 7702 |
| 18 | 14591 |
| 19 | 27585 |
| 20 | 52476 |
| 21 | 99868 |
| 22 | 190733 |
| 23 | 364711 |
| 24 | 699238 |
| 25 | 1342170 |
| 26 | 2581413 |
| 27 | 4971053 |
| 28 | 9587564 |
| 29 | 18512776 |
| 30 | 35792551 |
| 31 | 69273651 |
| 32 | 134219778 |
| 33 | 260301158 |
[0,0,0,1,2,4,9,15,30,54,101,181,344,624,1173,2183, 4106,7702,14591,27585,52476,99868,190733,364711, 699238,1342170,2581413,4971053,9587564,18512776, 35792551,69273651,134219778,260301158] |