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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 21 |
| 4 | 244 |
| 5 | 4002 |
| 6 | 84909 |
| 7 | 2209947 |
| 8 | 68121822 |
| 9 | 2425846806 |
| 10 | 97969327890 |
| 11 | 4423628854404 |
| 12 | 220806455598561 |
| 13 | 12072207455321168 |
| 14 | 717431790926502954 |
| 15 | 46045783798588216767 |
| 16 | 3174068594948910976851 |
| 17 | 233875508656473241657578 |
[1,1,3,21,244,4002,84909,2209947,68121822, 2425846806,97969327890,4423628854404, 220806455598561,12072207455321168, 717431790926502954,46045783798588216767, 3174068594948910976851,233875508656473241657578] |