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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 10 |
| 4 | 42 |
| 5 | 136 |
| 6 | 594 |
| 7 | 2142 |
| 8 | 9669 |
| 9 | 36983 |
| 10 | 170702 |
| 11 | 678033 |
| 12 | 3178156 |
| 13 | 12960483 |
| 14 | 61428141 |
| 15 | 255417323 |
| 16 | 1220640672 |
| 17 | 5151889022 |
| 18 | 24776988418 |
| 19 | 105826225847 |
| 20 | 511470203676 |
| 21 | 2205862516479 |
| 22 | 10703248215557 |
| 23 | 46535014900193 |
| 24 | 226518790021613 |
| 25 | 991596972703300 |
| 26 | 4839515407094849 |
| 27 | 21309760209644446 |
[1,1,4,10,42,136,594,2142,9669,36983,170702, 678033,3178156,12960483,61428141,255417323, 1220640672,5151889022,24776988418,105826225847, 511470203676,2205862516479,10703248215557, 46535014900193,226518790021613,991596972703300, 4839515407094849,21309760209644446] |