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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 14 |
| 4 | 65 |
| 5 | 448 |
| 6 | 3136 |
| 7 | 32028 |
| 8 | 251922 |
| 9 | 2891801 |
| 10 | 30684797 |
| 11 | 464651863 |
| 12 | 5434037232 |
| 13 | 92246217970 |
| 14 | 1379368317328 |
| 15 | 29135744093948 |
| 16 | 414052904722966 |
| 17 | 8546218817446727 |
| 18 | 152935671938144301 |
| 19 | 3857215760145872627 |
| 20 | 70913916905782150177 |
| 21 | 1881992311219764068420 |
[1,1,3,14,65,448,3136,32028,251922,2891801, 30684797,464651863,5434037232,92246217970, 1379368317328,29135744093948,414052904722966, 8546218817446727,152935671938144301, 3857215760145872627,70913916905782150177, 1881992311219764068420] |