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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 7 |
| 5 | 53 |
| 6 | 215 |
| 7 | 1895 |
| 8 | 12122 |
| 9 | 132205 |
| 10 | 1144627 |
| 11 | 14912291 |
| 12 | 164213696 |
| 13 | 2477432371 |
| 14 | 33228911417 |
| 15 | 569758644845 |
| 16 | 9014907260096 |
| 17 | 173288317530505 |
| 18 | 3159048447572983 |
| 19 | 67337939660404735 |
| 20 | 1389152842003647000 |
| 21 | 32545156966898107751 |
| 22 | 749093688443752763861 |
| 23 | 19146060950641834007177 |
[0,1,1,4,7,53,215,1895,12122,132205,1144627, 14912291,164213696,2477432371,33228911417, 569758644845,9014907260096,173288317530505, 3159048447572983,67337939660404735, 1389152842003647000,32545156966898107751, 749093688443752763861,19146060950641834007177] |