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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 3 |
| 6 | 13 |
| 7 | 54 |
| 8 | 216 |
| 9 | 884 |
| 10 | 3575 |
| 11 | 14527 |
| 12 | 58925 |
| 13 | 239168 |
| 14 | 970540 |
| 15 | 3938720 |
| 16 | 15984049 |
| 17 | 64866679 |
| 18 | 263242213 |
| 19 | 1068291334 |
| 20 | 4335346204 |
| 21 | 17593728716 |
| 22 | 71398977047 |
| 23 | 289751765259 |
| 24 | 1175872383597 |
| 25 | 4771932491856 |
| 26 | 19365485592728 |
| 27 | 78589131949936 |
| 28 | 318930895432049 |
| 29 | 1294287308406283 |
[0,0,0,1,3,13,54,216,884,3575,14527,58925,239168, 970540,3938720,15984049,64866679,263242213, 1068291334,4335346204,17593728716,71398977047, 289751765259,1175872383597,4771932491856, 19365485592728,78589131949936,318930895432049, 1294287308406283] |