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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 9 |
| 6 | 28 |
| 7 | 66 |
| 8 | 190 |
| 9 | 946 |
| 10 | 4441 |
| 11 | 16650 |
| 12 | 67069 |
| 13 | 380795 |
| 14 | 2220697 |
| 15 | 11142307 |
| 16 | 58133022 |
| 17 | 380165427 |
| 18 | 2581541092 |
| 19 | 15919859932 |
| 20 | 101602799146 |
| 21 | 758173118356 |
| 22 | 5826902270129 |
| 23 | 42158185020684 |
| 24 | 316416126945385 |
| 25 | 2656178496077301 |
| 26 | 22725296418141937 |
| 27 | 187568834724460765 |
[1,1,1,1,2,9,28,66,190,946,4441,16650,67069, 380795,2220697,11142307,58133022,380165427, 2581541092,15919859932,101602799146,758173118356, 5826902270129,42158185020684,316416126945385, 2656178496077301,22725296418141937, 187568834724460765] |