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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 30 |
| 5 | 112 |
| 6 | 464 |
| 7 | 2109 |
| 8 | 10411 |
| 9 | 55351 |
| 10 | 314772 |
| 11 | 1903878 |
| 12 | 12189432 |
| 13 | 82274309 |
| 14 | 583389847 |
| 15 | 4332513061 |
| 16 | 33607736990 |
| 17 | 271657081128 |
| 18 | 2283282938288 |
| 19 | 19916981288017 |
| 20 | 179994994948647 |
| 21 | 1682624910161483 |
| 22 | 16247280435775188 |
| 23 | 161833756265886822 |
| 24 | 1660836884761337248 |
[0,1,3,9,30,112,464,2109,10411,55351,314772, 1903878,12189432,82274309,583389847,4332513061, 33607736990,271657081128,2283282938288, 19916981288017,179994994948647,1682624910161483, 16247280435775188,161833756265886822, 1660836884761337248] |