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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 25 |
| 5 | 87 |
| 6 | 323 |
| 7 | 1213 |
| 8 | 4616 |
| 9 | 18122 |
| 10 | 73034 |
| 11 | 296118 |
| 12 | 1201985 |
| 13 | 4944712 |
| 14 | 20699593 |
| 15 | 87039567 |
| 16 | 364582540 |
| 17 | 1536503788 |
| 18 | 6577636822 |
| 19 | 28301509234 |
| 20 | 120717294622 |
| 21 | 515067346615 |
| 22 | 2238588931727 |
| 23 | 9820016463003 |
| 24 | 42372035446400 |
| 25 | 181068476007679 |
| 26 | 795531553724263 |
| 27 | 3577424216585403 |
[1,1,3,8,25,87,323,1213,4616,18122,73034,296118, 1201985,4944712,20699593,87039567,364582540, 1536503788,6577636822,28301509234,120717294622, 515067346615,2238588931727,9820016463003, 42372035446400,181068476007679,795531553724263, 3577424216585403] |