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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 14 |
| 5 | 48 |
| 6 | 171 |
| 7 | 614 |
| 8 | 2270 |
| 9 | 8518 |
| 10 | 32567 |
| 11 | 126168 |
| 12 | 495079 |
| 13 | 1962752 |
| 14 | 7853581 |
| 15 | 31672502 |
| 16 | 128622480 |
| 17 | 525523990 |
| 18 | 2158818376 |
| 19 | 8911039462 |
| 20 | 36941520279 |
| 21 | 153740822408 |
| 22 | 642085403709 |
| 23 | 2690217364606 |
| 24 | 11304538078369 |
| 25 | 47630350694248 |
| 26 | 201181246749072 |
| 27 | 851690546714230 |
[0,1,4,14,48,171,614,2270,8518,32567,126168, 495079,1962752,7853581,31672502,128622480, 525523990,2158818376,8911039462,36941520279, 153740822408,642085403709,2690217364606, 11304538078369,47630350694248,201181246749072, 851690546714230] |