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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 4 |
| 6 | 11 |
| 7 | 30 |
| 8 | 96 |
| 9 | 339 |
| 10 | 1316 |
| 11 | 5584 |
| 12 | 25733 |
| 13 | 128025 |
| 14 | 683949 |
| 15 | 3905083 |
| 16 | 23731187 |
| 17 | 152934464 |
| 18 | 1041782238 |
| 19 | 7479469995 |
| 20 | 56448098958 |
| 21 | 446768591341 |
| 22 | 3700276748921 |
| 23 | 32007269639380 |
| 24 | 288630046441757 |
| 25 | 2708888570942365 |
| 26 | 26419890078249485 |
| 27 | 267389254029561667 |
[1,1,1,2,4,11,30,96,339,1316,5584,25733,128025, 683949,3905083,23731187,152934464,1041782238, 7479469995,56448098958,446768591341,3700276748921, 32007269639380,288630046441757,2708888570942365, 26419890078249485,267389254029561667] |