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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 2 |
| 4 | 6 |
| 5 | 11 |
| 6 | 33 |
| 7 | 86 |
| 8 | 278 |
| 9 | 873 |
| 10 | 2938 |
| 11 | 9904 |
| 12 | 34321 |
| 13 | 119673 |
| 14 | 422725 |
| 15 | 1502590 |
| 16 | 5381671 |
| 17 | 19377063 |
| 18 | 70138385 |
| 19 | 254978018 |
| 20 | 930709334 |
| 21 | 3409356533 |
| 22 | 12530190100 |
| 23 | 46188325542 |
| 24 | 170723964752 |
| 25 | 632624262841 |
| 26 | 2349655631568 |
| 27 | 8745690221340 |
| 28 | 32617408075856 |
[1,2,2,6,11,33,86,278,873,2938,9904,34321,119673, 422725,1502590,5381671,19377063,70138385, 254978018,930709334,3409356533,12530190100, 46188325542,170723964752,632624262841, 2349655631568,8745690221340,32617408075856] |