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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 10 |
| 4 | 49 |
| 5 | 271 |
| 6 | 1861 |
| 7 | 14218 |
| 8 | 125945 |
| 9 | 1222525 |
| 10 | 13274551 |
| 11 | 155993586 |
| 12 | 2006410033 |
| 13 | 27654327715 |
| 14 | 411146102641 |
| 15 | 6498852124066 |
| 16 | 109654601938801 |
| 17 | 1954603251773273 |
| 18 | 36899871955766155 |
| 19 | 732088187170903162 |
| 20 | 15288727416236948241 |
| 21 | 334089096072180624631 |
[1,1,3,10,49,271,1861,14218,125945,1222525, 13274551,155993586,2006410033,27654327715, 411146102641,6498852124066,109654601938801, 1954603251773273,36899871955766155, 732088187170903162,15288727416236948241, 334089096072180624631] |