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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 23 |
| 5 | 76 |
| 6 | 278 |
| 7 | 1014 |
| 8 | 3792 |
| 9 | 14239 |
| 10 | 53516 |
| 11 | 203219 |
| 12 | 774991 |
| 13 | 2970994 |
| 14 | 11427400 |
| 15 | 44044577 |
| 16 | 170220249 |
| 17 | 659281162 |
| 18 | 2558782202 |
| 19 | 9948657480 |
| 20 | 38736609234 |
| 21 | 151032841208 |
| 22 | 589597013958 |
| 23 | 2304279342902 |
| 24 | 9015037085068 |
| 25 | 35302506743196 |
| 26 | 138362112861968 |
[1,1,2,7,23,76,278,1014,3792,14239,53516,203219, 774991,2970994,11427400,44044577,170220249, 659281162,2558782202,9948657480,38736609234, 151032841208,589597013958,2304279342902, 9015037085068,35302506743196,138362112861968] |