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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 2 |
| 6 | 14 |
| 7 | 79 |
| 8 | 430 |
| 9 | 2161 |
| 10 | 10162 |
| 11 | 45282 |
| 12 | 192945 |
| 13 | 790849 |
| 14 | 3138808 |
| 15 | 12116550 |
| 16 | 45675153 |
| 17 | 168661704 |
| 18 | 611701138 |
| 19 | 2183635232 |
| 20 | 7686541342 |
| 21 | 26720976964 |
| 22 | 91856241351 |
| 23 | 312594121721 |
| 24 | 1054104924270 |
[0,0,0,0,2,14,79,430,2161,10162,45282,192945, 790849,3138808,12116550,45675153,168661704, 611701138,2183635232,7686541342,26720976964, 91856241351,312594121721,1054104924270] |