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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 20 |
| 5 | 71 |
| 6 | 266 |
| 7 | 1033 |
| 8 | 4133 |
| 9 | 16919 |
| 10 | 70543 |
| 11 | 298461 |
| 12 | 1277895 |
| 13 | 5525308 |
| 14 | 24086364 |
| 15 | 105730896 |
| 16 | 466907516 |
| 17 | 2072662801 |
| 18 | 9243364577 |
| 19 | 41392064353 |
| 20 | 186040133239 |
| 21 | 838962247305 |
| 22 | 3794801298127 |
| 23 | 17211872676042 |
| 24 | 78262816746849 |
[1,2,6,20,71,266,1033,4133,16919,70543,298461, 1277895,5525308,24086364,105730896,466907516, 2072662801,9243364577,41392064353,186040133239, 838962247305,3794801298127,17211872676042, 78262816746849] |