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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 21 |
| 5 | 55 |
| 6 | 216 |
| 7 | 659 |
| 8 | 2773 |
| 9 | 9274 |
| 10 | 40660 |
| 11 | 144482 |
| 12 | 650821 |
| 13 | 2415406 |
| 14 | 11092583 |
| 15 | 42543680 |
| 16 | 198221801 |
| 17 | 780032966 |
| 18 | 3674928118 |
| 19 | 14762312411 |
| 20 | 70157373141 |
| 21 | 286612381208 |
| 22 | 1371638239237 |
| 23 | 5682633709809 |
| 24 | 27349812752792 |
| 25 | 114658455891289 |
| 26 | 554420794389554 |
| 27 | 2347945946536543 |
| 28 | 11397643763639976 |
[1,1,3,6,21,55,216,659,2773,9274,40660,144482, 650821,2415406,11092583,42543680,198221801, 780032966,3674928118,14762312411,70157373141, 286612381208,1371638239237,5682633709809, 27349812752792,114658455891289,554420794389554, 2347945946536543,11397643763639976] |