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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 11 |
| 5 | 43 |
| 6 | 182 |
| 7 | 806 |
| 8 | 3687 |
| 9 | 17297 |
| 10 | 82753 |
| 11 | 402207 |
| 12 | 1980407 |
| 13 | 9857715 |
| 14 | 49522564 |
| 15 | 250768564 |
| 16 | 1278600022 |
| 17 | 6558731904 |
| 18 | 33823966611 |
| 19 | 175264755549 |
| 20 | 912043488146 |
| 21 | 4764361204130 |
| 22 | 24974974692240 |
| 23 | 131335127655540 |
[0,1,1,3,11,43,182,806,3687,17297,82753,402207, 1980407,9857715,49522564,250768564,1278600022, 6558731904,33823966611,175264755549,912043488146, 4764361204130,24974974692240,131335127655540] |