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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 9 |
| 3 | 50 |
| 4 | 203 |
| 5 | 1081 |
| 6 | 5491 |
| 7 | 30100 |
| 8 | 165841 |
| 9 | 941019 |
| 10 | 5401905 |
| 11 | 31489071 |
| 12 | 185415573 |
| 13 | 1102594901 |
| 14 | 6608330597 |
| 15 | 39889119774 |
| 16 | 242247852507 |
| 17 | 1479208979061 |
| 18 | 9075878125131 |
| 19 | 55927537029301 |
| 20 | 345980015040103 |
| 21 | 2147862197235447 |
[1,6,9,50,203,1081,5491,30100,165841,941019, 5401905,31489071,185415573,1102594901,6608330597, 39889119774,242247852507,1479208979061, 9075878125131,55927537029301,345980015040103, 2147862197235447] |