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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 5 |
| 5 | 21 |
| 6 | 81 |
| 7 | 302 |
| 8 | 1107 |
| 9 | 4027 |
| 10 | 14608 |
| 11 | 52988 |
| 12 | 192501 |
| 13 | 701065 |
| 14 | 2560806 |
| 15 | 9384273 |
| 16 | 34504203 |
| 17 | 127288011 |
| 18 | 471102318 |
| 19 | 1749063906 |
| 20 | 6513268401 |
| 21 | 24323719461 |
| 22 | 91081800417 |
| 23 | 341929853235 |
| 24 | 1286711419527 |
| 25 | 4852902998951 |
| 26 | 18341683253676 |
[0,0,0,1,5,21,81,302,1107,4027,14608,52988,192501, 701065,2560806,9384273,34504203,127288011, 471102318,1749063906,6513268401,24323719461, 91081800417,341929853235,1286711419527, 4852902998951,18341683253676] |