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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 9 |
| 6 | 20 |
| 7 | 46 |
| 8 | 105 |
| 9 | 243 |
| 10 | 556 |
| 11 | 1269 |
| 12 | 2873 |
| 13 | 6486 |
| 14 | 14555 |
| 15 | 32556 |
| 16 | 72517 |
| 17 | 161032 |
| 18 | 356396 |
| 19 | 786610 |
| 20 | 1731228 |
| 21 | 3800671 |
| 22 | 8323071 |
| 23 | 18184612 |
| 24 | 39640861 |
| 25 | 86228722 |
| 26 | 187177522 |
| 27 | 405493600 |
| 28 | 876728251 |
| 29 | 1892008416 |
| 30 | 4075471821 |
| 31 | 8762948485 |
[1,1,1,2,4,9,20,46,105,243,556,1269,2873,6486, 14555,32556,72517,161032,356396,786610,1731228, 3800671,8323071,18184612,39640861,86228722, 187177522,405493600,876728251,1892008416, 4075471821,8762948485] |