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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 1 |
| 3 | 7 |
| 4 | 9 |
| 5 | 21 |
| 6 | 148 |
| 7 | 281 |
| 8 | 997 |
| 9 | 3037 |
| 10 | 33036 |
| 11 | 76275 |
| 12 | 352586 |
| 13 | 1466713 |
| 14 | 6840499 |
| 15 | 96591514 |
| 16 | 293606525 |
| 17 | 1501812845 |
| 18 | 7541619580 |
| 19 | 45272015807 |
| 20 | 252241209910 |
| 21 | 5166271223047 |
| 22 | 18007882089737 |
| 23 | 113281855815782 |
| 24 | 613837386060838 |
| 25 | 4188738630903441 |
| 26 | 29051626448346113 |
[1,2,1,7,9,21,148,281,997,3037,33036,76275,352586, 1466713,6840499,96591514,293606525,1501812845, 7541619580,45272015807,252241209910,5166271223047, 18007882089737,113281855815782,613837386060838, 4188738630903441,29051626448346113] |