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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 21 |
| 5 | 58 |
| 6 | 222 |
| 7 | 724 |
| 8 | 2920 |
| 9 | 10477 |
| 10 | 43806 |
| 11 | 167427 |
| 12 | 718675 |
| 13 | 2872493 |
| 14 | 12577258 |
| 15 | 51963651 |
| 16 | 231079431 |
| 17 | 979298120 |
| 18 | 4409345740 |
| 19 | 19064971826 |
| 20 | 86718435679 |
| 21 | 381062416397 |
| 22 | 1748022746120 |
| 23 | 7783935769853 |
| 24 | 35962860869620 |
| 25 | 161925742219489 |
| 26 | 752704839947332 |
| 27 | 3420971366786050 |
| 28 | 15986429779564805 |
[1,1,3,6,21,58,222,724,2920,10477,43806,167427, 718675,2872493,12577258,51963651,231079431, 979298120,4409345740,19064971826,86718435679, 381062416397,1748022746120,7783935769853, 35962860869620,161925742219489,752704839947332, 3420971366786050,15986429779564805] |